The answer is B. Why not Answer A? Gyroplanes and helicopters are “classes” of aircraft within the rotorcraft category, and airships and balloons are classes in the lighter-than-air category. Answer C doesn’t fly because it gives airplane class ratings (see FAR 61.5).

The regulation states that airplane, rotorcraft, glider, and lighter-than-air categories, among others, are placed on (non-student) pilot certificates “when an applicant satisfactorily accomplishes the training and certification requirements for the rating sought.” If you take and pass your private pilot practical test in a single-engine airplane on wheels (not floats), your pilot certificate will have category and class ratings of “airplane, single-engine, land” (ASEL). Take the ride in a single-engine seaplane and you will be rated for airplane, single-engine sea (ASES). In case someone asks, sport pilot certificates do not list category and class ratings.

That’s how “category” works “with respect to the certification, ratings, privileges, and limitations of airmen,” according to Chapter 1 of the Pilot’s Handbook of Aeronautical Knowledge.

“Category” has another significance as applied to aircraft, grouping them “based upon intended use or operating limitations. Examples include: transport, normal, utility, acrobatic, limited, restricted, and provisional” categories. You may know from studying your trainer’s pilot’s operating handbook that some trainers are approved for utility category as well as normal category operation, subject to manufacturers’ limitations.

A pink slip is no fun after a practical test, but a pink aircraft airworthiness certificate signifies an aircraft belonging to the primary, restricted, or limited category, or a light sport aircraft. Pink certificates are also issued “as provisional airworthiness certificates, special flight permits (ferry permits), and for experimental aircraft.” (Pilot’s Handbook of Aeronautical Knowledge Page 3-2.) Standard airworthiness certificates are white.

If you move on to earn an instrument rating, you will encounter another FAA application of “category.” Pilots use aircraft approach categories to determine minimum altitudes and visibilities for flying instrument approach procedures.

Categories also differentiate airspace, GPS systems, and radar facilities into functional groupings.

Tricky? One way to put the term in context when tackling a test question or researching a regulation is to note, as the knowledge-test question above does, whether “category” is being used “with respect to” airman certification, aircraft certification, or an operating limitation.