which of the following notes is not middle c?\na.\nb.\nc.\nd.

Brief Explanations:

Middle - C on the treble clef is the first ledger line below the staff, and on the bass clef is the first ledger line above the staff. Option A shows a note on the treble - clef's first ledger line (middle - C). Option B shows a note on the bass - clef's first ledger line (middle - C). Option D also shows a note on the bass - clef's first ledger line (middle - C). Option C has a time signature and a note that is not in the position of middle - C on either clef.

Answer:

C.