Which of these characteristics is common only at the embryonic stage of fish and humans, and is suggestive of a common ancestor between the two? a) presence of lungs b) presence of a tail c) presence of gill slits eliminate d) presence of a vertebral column

The answer is; C

Most often some ancestral characters are preserved in an organism's development hence can be used to study evolutionary relationships. One of these features is the gill slits in embryos. These have been used to postulate that all land organisms, that exhibit gill slits in their embryonic development, emanated from a common fish ancestor. In humans, these gill slits later develop in the pharyngeal.

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a

the answer for this question would be d. glaciers