Advantage(s) to using surveys as opposed to experiments is (are) that
(a) surveys are generally cheaper to conduct(b) its generally easier to conclude cause and effect from surveys
(c) surveys are generally not subject to bias(d) surveys involve use of randomization(e) surveys can make use of stratifications

(A) Surveys are generally cheaper to conduct.

Explanation:

Both surveys and experiments are valid means to scientifically establish data about groups of people and how the way specific variables influence them. A survey examines the way a variable we have no control over has affected, for example, a group of people. In an experiment, one of the variables is manipulated while the other one is measured.

Surveys are comparatively inexpensive, especially if they are online surveys, and even if incentives are provided to participants.

early settlements on the subcontinent. both the indus and the ganges rivers carried rich silt from the mountains to the plains. when the rivers flooded, the silt spread over the plains and made the soil in the river valleys fertile for farming.

i believe the answer is: returns on investments, no wages

people who belong in upper class society would most likely get there by obtaining multiple source of income, which a certain percentage of ownership for businesses. since most of them are job creator, they would most likely get their money from profit, not wages.