Two species of garter snakes live in the same geographic area. One lives mainly in water and the other mainly on land; therefore, they rarely encounter each other and do not interbreed. What type of isolation is this?

The correct answer is ecological isolation.

Explanation:

The condition when two species in spite of living in the same region, exhibits certain characteristics, which inhibits them from mating with each other is termed as reproductive isolation. The obstructions or the causes that prevent them from interbreeding is known as isolating mechanisms.  

The given case is an example of ecological isolation and is one of the forms of reproductive isolation. Habitat or ecological isolation refers to the phenomenon in which two species cannot mate with each other as they thrive in two distinct locations. Like as mentioned, two species of garter snakes though coming from the same geographical area cannot interbreed, as one of them is living in the land and the other one in the water.  

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)