Which of the following is not a main orchestral group or family?

A. Vibraphones

B. Strings

C. Brass

D. Percussion

Percussion is not one of the main orchestral groups, it is a group containing things such as the drums.

The answer is A. Vibraphones.

strings is the family that includes violins, cellos, guitars, etc.

brass includes trumpets and the tuba, etc.

percussion includes drums, tambourines, etc.