Which of the following is not required during post transcriptional processing in eukaryotes?

$A$: Kornberg enzyme is associated with the removal of primers and thyminedimer.

$R$: $DNA$ polymersase I does exonuclease activity in $5^{\prime} \rightarrow 3^{\prime}$ and $3^{\prime} \rightarrow 5^{\prime}$ directions.

Repetitive sequences are stretches of $DNA$ with repeated bases many times in a genome, but

$(a)$ These sequences are of no transcriptional function
$(b)$ These are associated with euchromatin region
$(c)$ These helps to identify a person on the basis of its $DNA$ specificity

Genes of interest can be selected from a genomic library by using

Lampbrush chromosomes are found inside