Answer:
B. Simple random sampling.
Step-by-step explanation:
From the question we are informed about a research team conducts a survey to determine the area of land used for farming in Iowa. The team randomly selects house addresses and sends the survey by mail. In this case, the type of sampling method used is the Simple random sampling. A simple random sample can be regarded as a subset of a statistical population, whereby each member of this subset posses an equal probability of them being chosen. A simple random sample can be portrayed as an unbiased representation of a group.
Simple random sampling is utilized in to culling smaller sample size out of larger population so that it can be used to research and make generalizations as regards larger group.