Refer to figure.
For ditching the general advice is:

• At minimum speed: Lowest forward speed on impact with the water.
• Full flap: Allowing for the lowest possible forward speed.
• Gear retracted: Minimise the chance of cartwheeling / turning the aircraft over.
• Land parallel to any swell: See the attached figure, this technique minimises the chance of structural failure on impact with the sea. Accept a cross wind unless the wind strength is high, then ditching into wind is advisable.

Lookin at the answer options:

The aircraft will skim the surface of the water until it slows --> INCORRECT. The gear will create immediate drag and a rapid deceleration.

The aircraft will experience sudden deceleration --> INCORRECT. Tricky one from the examiner as this is not wrong, but is not as complete an answer as the correct one given here.

The aircraft will experience sudden deceleration and is likely to pitch over --> CORRECT. The most complete answer. The gear will drag in the water causing a rapid deceleration and is likely to cause the aircraft to pitch over.

The wings are likely to become detached from the airframe --> INCORRECT. This could happen but is not the primary concern when ditching with fixed gear.

The following is a fuller list of generally accepted considerations and techniques for ditching:

• Reduce Aircraft Weight. A lighter aircraft allows a lower approach speed and will probably remain afloat higher in the water and for longer thus facilitating occupant evacuation. Burning off or dumping fuel also has the advantage of increasing buoyancy in some aircraft types by creating a larger air mass held within the fuel tanks.
• Configuration. Gear up is the optimum configuration for ditching. Most manufacturers recommend the maximum deployment of available flaps is desirable to minimise approach speed.
• In ideal conditions (smooth water or very long swells) land into the wind. This will ensure the minimum possible touchdown speed and help minimise impact damage. Where the swell is more marked, it may be advisable to ditch along the swell accepting a crosswind component and the higher touchdown speed, thus minimising the potential for nosing into the face of the rising swell. The best touchdown point is on the top of the swell with the second best on the back of the swell. Aim to remain well clear of the advancing face of the swell.