In Bacterial Ribosomes,a Small 30S Subunit and a Large 50S

Multiple Choice

In bacterial ribosomes,a small 30S subunit and a large 50S subunit come together to produce the functional 70S ribosome.Why isn't it an 80S ribosome?

A) The ribosome will become an 80S complex when the protein it is producing starts to be formed.
B) Additional factors are required for protein synthesis.When these are put with the ribosome,it will become an 80S ribosome complex.
C) S stands for Svedberg units,which indicates the relative rate of sedimentation due to size,weight,and shape of a particle.The numbers aren't strictly additive.
D) A portion of the larger 50S subunit is detached as the ribosomes come together,making the final complex a 70S ribosome instead of an 80S ribosome.