Refer to figures. 
Learning Objective 010.07.01.03.02: Describe the various rules and services that apply to the various classes of airspace. 
Source: ICAO Annex 11, Chapter 2, 2.6 Classification of airspaces and Annex 11, Appendix 4 
Note: This question has also seen in UK CAA exams as a “drop-down” with two drop-down menus, one for (Class) F and one for IFR.

Class F airspace is uncontrolled "advisory" airspace. In fact, it is a bit of a "grey area" of airspace and the UK and US (amongst other countries) have actually removed its usage completely, changing those areas of airspace to class E or class G.

According to ICAO, however, within class F airspace, both IFR and VFR flights are permitted, with all participating IFR flights receiving an air traffic advisory service and all flights receiving a flight information service if requested.