A clinal distribution is one in which:. a. a biological trait or allele frequencies show a gradation over geographic space
b. a biological trait or allele frequencies show no gradation between populations
c. there is little variation in a biological trait or allele from north to south
d. the same frequency in a biological trait or allele is found everywhere

the correct answer is d

the potatoes have high sugar concentrations and although these potatoes were different we could seethe effects that their sugar concentrations had in different environments. for example, the potatoes in sample a, were placed in pure water. this created a hypertonic environment and caused the potatoes to draw in water from its surroundings. we saw the opposite happen with the potatoes in sample b when placed in the sodium chloride solution. the potatoes in this case were in a hypotonic solution and therefore lost water to their surroundings.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.  

that's all i luck!