Final answer:
Enzymatic RNA molecules are known as ribozymes, which include rRNA due to its peptidyl transferase activity in (B) ribosomes.
Step-by-step explanation:
The RNA molecules known for their catalytic abilities are called ribozymes. These ribozymes are ribonucleic acids that catalyze reactions in a manner similar to protein enzymes. An example of a ribozyme is the ribosomal RNA (rRNA) itself, as it is a major component of ribosomes which are also classified as ribozymes due to the enzymatic activity of rRNA, particularly in the peptidyl transferase function that facilitates the bonding of amino acids during protein synthesis.
On the other hand, mRNA (messenger RNA) carries genetic information from DNA to the ribosome, where this information is used to make proteins, and tRNA (transfer RNA) brings the correct amino acids into place on the ribosome according to the sequence coded in the mRNA, but neither of these have catalytic functions. Hence, the answer to the question would be that enzymatic RNA molecules are called ribozymes, aligning with option A.