Different versions of the same gene (represented
with letters)?

Different versions of a gene are called alleles. Alleles are described as either dominant or recessive depending on their associated traits

Explanation:

the answer to your question is:

c. complementary base-pairing

lizards have adapted to life in the desert. some desert lizards have toes with spiny scales to them run across the sand without sinking. some use the sand to hide from predators, or to search for small animals that they prey upon.