You Are Studying a Eukaryotic Gene Whose Initial Transcript Is

You are studying a eukaryotic gene whose initial transcript is 1500 nucleotides in length.The mature mRNA derived from the gene is 1200 nucleotides in length.What is the most probable reason for the discrepancy?

A) a mutation that results in a shorter product
B) removal of introns
C) removal of exons
D) mRNA breakage
E) A mutation that results in a shorter product or mRNA breakage could have occurred.