Q. What is the role of DNA ligase in DNA replication ?

A) add more nucleotides to the growing strand one at a time
B) ligate base to sugar to phosphate in a nucleotide
C) join Okazaki fragments to one another
D) remove incorrectly paired bases

... Answer is C). join Okazaki fragments to one another

Explanation :

DNA ligases play essential roles in replication, recombination and repair since they join broken DNA strands by catalysing the formation of a phosphodiester bond between the 3' hydroxyl end of one stand and the 5' phosphate end of another.