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

Answer: RNA transcripts become shorter on average

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.

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 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.