Question

How are musical instruments grouped?

Answer 1

Musical instruments are grouped by how they produce the pitch.

Pitch is the highness or lowness of a tone.

Answer 2

A and B are equivalent.  That's one way instruments are often grouped. (the "sopranos", the "altos", the "bass")

C is another way instruments are often grouped; (the "woods", the "brass")

D is another way instruments are often grouped; (the "strings", the "percussions")