Translation involves several different types of tRNA molecules. Which statement best describes how tRNA molecules assemble amino acids into a polypeptide?
A. One tRNA molecule assembles the polypeptide, and the others assist it.
B. Three tRNA molecules assemble the polypeptide, and the others assist them.
C. Each tRNA molecules assembles a different part of the polypeptide, and all at the same time.
D. The different tRNA molecules act in a specific order, one after the other like an assembly line.