Which statement about the 5'cap and mRNA processing is TRUE?

A)The addition of a 5' cap to mRNA occurs while the pre-mRNA is being made.
B)The 5' cap helps stabilize the mature mRNA.
C)The 5' cap prevents the degradation of mature mRNA.
D)The 5' cap is added to the pre-mRNA by splicesomes.
E)The 5'cap is a group of adenosine molecules.