The rare enol form of thymine pairs with guanine. If a thymidine within the DNA helix shifts to the enol form during replication, base pairing would change from a T-A base pair to a

a: the sheep and waste material both release carbon into the atmosphere.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

make   gliitsh plesea   !

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.