Researchers use the denaturation temperatures of hybrid double helices to compare evolutionary relatedness. Complementary strands denature at 95 degrees Celsius. A researcher engineers a hybrid double helix from two species, and it denatures at 93 degrees Celsius. What does this mean?

The strands of the hybrid helix are less complementary than the original helix.

Explanation:

Complementary DNA strands are bonded to each other through hydrogen bonding. The nitrogenous base adenine (A) forms 2 hydrogen bonds with thymine (T). Guanine forms 3 hydrogen bonds with cytosine. Due to the presence of 3 hydrogen bonds, GC rich regions of DNA or RNA are more strongly bonded.

Therefore, if the two strands will be less complementary or contain more AT rich regions, the double helix will denature or melt at a lower temperature.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

i think the answer would be d