Targeting certain structural features of eukaryotic mRNA can result in an inhibition of protein synthesis. Which one of the following describes a unique aspect of eukaryotic mRNA? A. A polyguanosine tail is found at the 3 ′ -end. B. The 5 ′ -end begins with a leader sequence that contains an adenine cap. C. The cap and tail of the mRNA are added posttranscriptionally. D. The leader sequence contains a guanosine cap at the 3 ′ -end of the mRNA. E. The poly(A) tail is found at the 3 ′ -end of the mRNA.