Introns Are Known to Contain Termination Codons (UAA, UGA, or UAG)

Introns are known to contain termination codons (UAA, UGA, or UAG) , yet these codons do not interrupt the coding of a particular protein. Why?

A) More than one termination codon is needed to stop translation.
B) These triplets cause frameshift mutations, but not termination.
C) Introns are removed from mRNA before translation.
D) UAA, UGA, and UAG are initiator codons, not termination codons.
E) Exons are spliced out of mRNA before translation.