As I was going through the most notorious list of questions for my test tomorrow I realized the absolute worst in my opinion is this one right here.

The question starts with "(most of) the members of BU17 of the gov emp union are computer programmers"

The correct answer is the choice "(most of) the members of BU17" which implies that this is a sufficient assumption

How can this even be possible.

Imagine the possible analogous question

Case 1: "Most of the members of the US Marines of the US military are expert at urban warfare"

VS

Case 2: "Most of the members of the special forces of the US military are expert at urban warfare"

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Case 1: Sentence whose blank is to be filled

[..] some of the US Military who work in Hanson building are experts in urban warfare since...

Most of the USMC work in Hanson building

Answer accepted because yes most of USMC expert in uw, and USMC is part of US Military.

Case2:

[..] some of the US Military who work in Hanson building are experts in urban warfare since...

Most of the Special Forces work in Hanson Building?

If there are 100,000 special forces across the world and there are only 50 Marines, how is this answer sure that the US Military personnel in Hanson Building have to contain Marines?

In so many words why is BU17 considered CANNOT BE SEVERED from the Government Employees Union condition?