Unicellular organisms have cell(s).

A. many
B. four
C. two
D. one

D. One

Explanation:

I just think of the "Uni" in unicellular as "Uno" ( which means one in Spanish)

~hope this method helped~

earliest

neumes above text

neumes

colored lines

neumes

4-line staff

f, c, or g clef

notes on 5-line staff with clef

mensuration (longas and breves)

time signature (perfect or half circle)

most recent

notes on 5-line staff

modern clefs

modern note values (whole, half, quarter, and so on)

modern time signature

italian words and abbreviations for dynamics and tempo

staccato, slurs, and so on