Question

all living organisms are composed of
a. at least three cells.
b. only one cell.
c. at least 100 cells.
d. one or more cells.

Explanation:

To solve this, we recall the cell theory which states that all living organisms are composed of one or more cells. Unicellular organisms (like bacteria) have one cell, while multicellular organisms have more than one. Option A is wrong as some organisms (unicellular) have 1 cell. Option B is wrong because multicellular organisms have more than one cell. Option C is wrong as many organisms (like bacteria, some protists) have far fewer than 100 cells. Option D correctly encompasses both unicellular (one cell) and multicellular (more than one cell) organisms.

Answer:

D. one or more cells.