For each of the following, state whether a one-proportion z-test or a two-proportion z test would be appropriate, and name the population(s).

a. A polling agency takes a random sample of voters in California to determine if a ballot proposition will pass.

b. A researcher asks a random sample of residents from coastal states and a random sample of residents of non-coastal states whether they favor increased offshore oil drilling. The researcher wants to determine if there is a difference in the proportion of residents who support off-shore drilling in the two regions.