Exon part of mRNA has code for the synthesis of
A. Protein
B. Lipid
D. Phospholipid
C. Carbohydrate

Hint: mRNA is the messenger RNA which is single stranded and has the genetic sequence of a gene. Exons and introns are the parts of RNA transcript. Exons are the coding regions whereas introns are non-coding regions. Protein synthesis usually occurs in two stages namely transcription and translation. Exons play an important role in the translation process.

Complete answer:
As I mentioned about protein synthesis, let us get into it. Firstly, transcription takes place in the nucleus where a RNA is formed by copying the genetic information from DNA. The so formed RNA is pre mRNA which enters the cytoplasm and initiates protein synthesis. In translation, there are three steps namely initiation, elongation and termination. The pre mRNA contains introns and exons, introns do not code for any amino acid and hence are removed by a process called splicing whereas exons code for proteins and are retained and that forms a mature mRNA. Amino acids are carried by tRNA and read by ribosomes and thus a protein is formed.

As exons are coding for proteins, the correct option is A.

Note:
Ribosomes are the cell organelles where protein synthesis takes place and are called as protein factories of the cell, rRNA is present inside this ribosome which will combine all the amino acids together to form a protein and for this reason rRNA is also called ribozyme. All the three RNAs which are mRNA, tRNA and rRNA play a very important role in the protein synthesis process.