Does it matter if resection occurs in the 5′ to 3′ direction or the 3′ to 5′ direction?
a) no, it is not important. resection may occur in every direction.
b) yes, it is important that the single-stranded dna have 5′ ends, so resection must occur in the 3′ to 5′ direction.
c) yes, it is important that the single-stranded dna have 3′ ends, so resection must occur in the 3′ to 5′ direction.
d) yes, it is important that the single-stranded dna have 3′ ends, so resection must occur in the 5′ to 3′ direction.

D) Yes, it is important that the single-stranded DNA have 3′ ends, so resection must occur in the 5′ to 3′ direction.

Explanation:

During homologous recombination, the exonucleases remove nucleotides from the free 5' ends of the DNA at the double-stranded breaks to create a double-strand gap.

Removal of more nucleotides from the free 5' ends creates 3' single-strand extension which in turn invades the intact homolog and pairs with its complementary sequence of the DNA. The invaded free 3' end is then extended by DNA polymerase to give rise to Holiday junctions.  

If the resection occurs in the opposite direction and creates overhangs with free 5' ends, the free 3' ends would not be available to serve as a primer to facilitate the replication.

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.