After digestion by restriction endonucleases DNA strands can be joined again by:

Ans. B. DNA Ligase(Ref: Harper 31/e page434)Enzymes involved in the DNA Replication1. Topoisomerases#Relieve torsional strain that results from helicase-induced unwinding of DNA.#Nicking Resealing Enzyme2. Helicase: ATP driven processive unwinding of DNA3. Single Strand Binding Protein (SSB)Prevent premature reannealing of dsDNA4. DNA Primase:#Initiates synthesis of RNA primers.#Special class of DNA dependent RNA Polymerase5. DNA Polymerase: Catalyse the chemical reaction of DNA Polymerisation. Synthesise DNA only in 5' to 3' direction.6. DNA Ligase: Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand.