Eukaryotic/mammalian DNA polymerases:
Pol $\alpha$: Contains primase activity, initiates synthesis and lagging strand primer elongation / gap filling (I)
Pol $\beta$: Involved in nuclear base excision repair (BER) (II)
Pol $\gamma$: Replicates and repairs mitochondrial DNA (III)
Pol $\delta$: Highly processive synthesis of the leading (and lagging) strand with proofreading (IV).

Because genetic code is triplet, 100 amino acids require at least $100 \times 3 = 300$ coding nucleotides plus initiation/termination codons. In eukaryotes, genes are interrupted (split genes) consisting of coding exons and intervening non-coding introns, as well as 5' and 3' untranslated regions (UTRs). Consequently, the actual eukaryotic gene size far exceeds 300 nucleotide bases. Reason (R) directly explains Assertion (A).

Upon entering the host bacterial cell, the circular single-stranded viral (+) DNA of viruses like bacteriophage $\phi\text{X174}$ or M13 is converted entirely into a double-stranded circular DNA intermediate (replicative form, RF I) by host DNA polymerase synthesizing the complementary (-) strand.

Telomeres are specialized repetitive DNA-protein structures located at the physical ends of linear eukaryotic chromosomes. Yeast, humans, and molds are all eukaryotes containing linear chromosomes with telomeres. E. coli is a bacterium with a closed circular chromosome, which lacks telomeres.