Why do you think the complementary base pairing between the two strands helps cells to detect and
repair errors in their DNA?

answer is

Explanation: Strands are complementary to each other, its mean that if one strand contain Adenine, Gunine and cytosine so on the other strand there will Thymine bond with Adenine, Cytosine with Gunanine and Gunanine with Cytosine. DNA molecules have an antiparallel structure - that is, the two strands of the helix run in ... Replication relies on complementary base pairing, that is the principle explained ... DNA replication occurs through the help of several enzymes.

Strands are complementary to each other, strand contain Adenine, Thymine Gunine and cytosine the other strand will also have this just in a different pattern. They have an antiparallel structure, a complementary strand is needed in order for replication to occur, along with the help of many enzymes.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.