Lots of opportunity for confusion, so let's look at the phraseology needed for this exam:

Skills Test: The flying test that completes training on a type rating course (with circuits to come).

Licence Proficiency Check (LPC): Renewal of the type rating / IR - done every 12 months.

Operator Proficiency Check (OPC): Effectively a mini IR and done between LPC's. The elements tested in an OPC are also done on the full LPC - so you end up doing 2 OPC's in every 12 months.

For example:

• Complete the skills test and type rating 31st December. Now valid for 12 months.
• LPC must be done by the following 31st December, but can be done (for operational flexibility) anytime within 3 months prior to this date, ie in October, November or December. The new validity would be for 12 months from the original expiry though.
• Mid year, you will need to do an OPC. In this example, by 30th June. Again there is a 3 month window to complete this check, allowing for operational flexibility.

Looking at the answer: 2 within a year, more than 3 months between checks --> CORRECT.

• You will do an OPC in mid year as it is valid for 6 months, and again as part of the annual LPC, so 2 in a year.
• Using the above example, it is possible to do the first OPC on the 30th June (at the latest) and then the second on the 1st October (at the earliest). There must always be at least 3 months between OPC's.

Finally, regarding the OPC / 12 month questions: This relates ONLY TO SPECIALISED TASKS. For example, an operator is certified to carry out the spraying of detergent on oil slicks. This is clearly a specialised task as it involves low level flying and unique operating conditions. This skill is tested every year by the operator using an OPC. Here, the crew will have to fly a dummy run and demonstrate competency in this operation.

Although this is also a check in proficiency by the operator (OPC), it is for a different skill set and by regulation, has a 12 month validity. More on this can be found below...

Note: If the question mentions specialised tasks, the answer is 12 months. If not, then we are talking about the mini IR and so it's 6 months and 2 in a year.

EASA AIR OPS
Regulation (EU) 2015/140
ORO.FC.230 Recurrent training and checking

(a) Each flight crew member shall complete recurrent training and checking relevant to the type or variant of aircraft on which they operate.

(b) Operator proficiency check

(1) Each flight crew member shall complete operator proficiency checks as part of the normal crew complement to demonstrate competence in carrying out normal, abnormal and emergency procedures.
(2) When the flight crew member will be required to operate under IFR, the operator proficiency check shall be conducted without external visual reference, as appropriate.
(3) The validity period of the operator proficiency check shall be six calendar months. For operations under VFR by day of performance class B aeroplanes conducted during seasons not longer than eight consecutive months, one operator proficiency check shall be sufficient. The proficiency check shall be undertaken before commencing commercial air transport operations.

EASA AIR OPS
ORO.FC.330 Recurrent training and checking — operator proficiency check

(a) Each flight crew member shall complete recurrent training and operator proficiency checks. In the case of specialised operations, the recurrent training and checking shall cover the relevant aspects associated with the specialised tasks described in the operations manual.

(b) Appropriate consideration shall be given when operations are undertaken under IFR or at night.

(c) The validity period of the operator proficiency check shall be 12 calendar months.