Which of the following statements is incorrect regarding post-transcriptional modifications in pre-mRNA?

Addition of a modified guanine nucleotide, known as the cap, to the 5' end of the pre-mRNA molecule to protect it from degradation.

Removing introns and joining exons in a pre-mRNA molecule to create a mature mRNA transcript.

The poly(A) tail is a sequence of adenine nucleotides added to the 5' end of the mRNA molecule.

Splicing allows for the production of multiple proteins from a single pre-mRNA transcript by selectively including or excluding exons.