This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
What is the function of DNA ligase? 
Select and explain. 
A. Unwinding (denaturation) of dsDNA to provide as ssDNA template, B. Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand, C. Initiation of DNA synthesis and elongation, D. Initiates synthesis of RNA primers
B: Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand
Answer: B: Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand 
Explanation: DNA ligase Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strandRef: Harpers Illustrated Biochemistry, 30th edition, page no: 382