(c) : Messenger $RNA$ or $mRNA$ has been named so because it carries the coded information from $DNA$ for the synthesis of proteins. It carries the coded information in a number ofbase triplets called codons. It is transcribed on $DNA$ by the enzyme $RNA$ polymerase. Hence, its base sequence is complementary to $DNA$ on which it has been synthesized. In eukaryotes each gene transcribes its own $mRNA$, therefore the number of $mRNAs$ corresponds to the number of genes. $rRNA$ is a type of $RNA$ that forms structural and functional components of ribosomes. $tRNA$ is a class of $RNA$ having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of $mRNA$. It binds with amino acids and transfers them to ribosomes.