Question

what is a polyribosome?
a ribosome that is able to \translate\ more than one type of mrna at the same time
a ribosome consisting of more than the typical 2 subunits
a group of several/many ribosomes associated with a single mrna strand
a ribosome that can bind to many trnas during translation

Explanation:

A polyribosome (also called polysome) is formed when multiple ribosomes attach to and translate a single mRNA strand simultaneously, increasing the efficiency of protein - synthesis.

Answer:

A group of several/many ribosomes associated with a single mRNA strand