Which of the following best describes a common change in RNA transcript length with age?

Answer: RNA transcripts become shorter on average

RNA transcripts become shorter on average ✓ — Correct. In aging cells, shorter RNA transcripts become relatively more common, while longer transcripts decline in relative abundance. This is a genome-wide pattern rather than a single-gene change, and it can reflect changes in how genes are transcribed or processed. The effect appears in multiple tissues and is not limited to one disease pathway.

RNA transcripts become longer on average — If aging damaged RNA processing, you might expect longer, unfinished transcripts to accumulate. But the trend seen in aging cells is a shift toward shorter RNA molecules, not longer ones. This choice confuses a possible mechanism with the observed outcome.

RNA transcript lengths stay roughly the same — It would be convenient if age-related changes in gene expression left transcript lengths untouched, but they do not. Aging cells predominantly show a shortening bias, with longer transcripts underrepresented. The idea that all lengths remain balanced misses this broad pattern.