In the Southern hybridization procedure,after electrophoresis the gel is treated with NaOH and then neutralized before blotting.What is the primary function of the alkaline treatment?

A)to cleave the DNA into smaller fragments to permit greater efficiency of transfer
B)to inactivate any restriction endonucleases that may be in the gel
C)to denature the duplex DNA to single-stranded DNA (ssDNA)
D)to neutralize any acidic phosphate groups that might prevent hybridization