Chargaff's rules ($A = T$ and $G = C$) apply only to double-stranded nucleic acids. Because most cellular RNAs are single-stranded, they do not follow 1:1 base pairing rules throughout their length, so guanine content is usually not equal to cytosine content. Therefore, Assertion (A) is false, while Reason (R) is true.

Topoisomerase-I enzymes catalyze relaxation of supercoiled DNA by creating a transient single-strand nick in duplex DNA (without requiring ATP) and changing the DNA linking number ($Lk$) in increments of one ($\Delta Lk = \pm 1$). Type II topoisomerases cleave both strands simultaneously and change $Lk$ by increments of 2.

The catalytic core of E. coli DNA polymerase III consists of three subunits: alpha (polymerase activity), epsilon (3'->5' proofreading exonuclease), and theta (stabilizes epsilon). In the official answer key, option 1: (A) and (B) only was designated as the correct answer.