Which of the following contains the three posttranscriptional modifications often seen in the maturation of mRNA in eukaryotes?

A) 5′-capping, 3′-poly(A) tail addition, splicing
B) 3′-capping, 5′-poly(A) tail addition, splicing
C) removal of exons, insertion of introns, capping
D) 5′-poly(A) tail addition, insertion of introns, capping
E) heteroduplex formation, base modification, capping