Which mRNA modification is likely absent if the mRNA is degrading prematurely from the 5 end of the mRNA?1) splicing together of exons.2) addition of the 3' polyadenylated tail.3) addition of the 7-methylguanosine cap to the 5 end.4) RNA editing.5) removal of introns.

3) addition of the 7-methylguanosine cap to the 5 end

Explanation:

The 7-methylguanosine (m7G) cap is a modified methylated version of the Guanosine (G) nucleotide which is located on the 5′-terminus of the eukaryotic messenger RNA (mRNA). The m7G cap plays a key role in mRNA translation in eukaryotic organisms, from yeasts to mammals. During mRNA processing, m7G cap is added at the 5' end in order to protect mRNA from degradation by nuclease enzymes. Moreover, this cap also enables the proper attachment of the mRNA molecule to the ribosome during protein synthesis.

a, i am pretty sure.