1aDNA gyrase can act to remove positive supercoils ligate ok

1aDNA gyrase can act to
   remove positive supercoils
   ligate okazaki fragments
   decatenate replicated chromosomes
   prime new DNA synthesis
   a) AND c)

1bDNA methylation

   marks the parental DNA strand
   marks the strand degraded in mismatch repair
   marks the strand retained in mismatch repair
   a AND b)
   a AND c)

Solution

1a. DNA gyrase is a class of topoisomerase, which removes positive supercoils in DNA while replication and allow replication fork to move freely. It also decatenate or remove supercoilings in Replicated DNA. So answer is A & C

1b. Answer A & C. DNA methylation prevents instant replication at Ori site, by methylating only Parental strand and it also helpful in DNA repair, by methylating parental stand, which is used as template by repair enzymes for the synthesis of Damaged DNA