Correct option is A
Explanation-
SINEs = Short Interspersed Nuclear Elements
They are a type of non-coding repetitive DNA found in eukaryotic genomes. Typically around 100–300 base pairs long. They are derived from tRNA or other small RNAs
SINEs are a subclass of retrotransposons, specifically non-autonomous retrotransposons. They do not encode reverse transcriptase but rely on other elements (like LINEs) for their mobility. They move via an RNA intermediate, which is reverse-transcribed and inserted back into the genome — a hallmark of retrotransposons.
Incorrect options-
Option b: "SINEs can transpose independently"
SINEs are non-autonomous and cannot transpose on their own. They require the reverse transcriptase and endonuclease provided by LINEs (e.g., LINE-1).
Option c: "SINEs can mobilize the neighboring LINE repeats"
The opposite is true — LINEs help SINEs transpose. SINEs lack coding regions and depend on LINE machinery.
Option d : "SINEs are normally transcribed by RNA polymerase I"
Most SINEs are transcribed by RNA polymerase III, not RNA polymerase I. This is due to their origin from tRNA genes.
Final answer - Option a - SINEs represent a class of retrotransposons
