Indicate whether each of the following descriptions applies to cilia (C), flagella (F), or both (B). Your answer would be a four-letter string composed of letters C, F, and B only, e.g. CCFB.
( ) They are short and present at high numbers per cell.
( ) They have a whiplike motion that resembles breaststroke in swimming.
( ) They are based on the axoneme structure.
( ) They are found in the epithelial cells of the human respiratory tract.