A subterranean system of tunnels developed in Persia connecting wells and dug using vertical shafts, designed to collect and transport water, sometimes over long distances, from highlands to low-lying farming land. a. True
b. False

experiments.

surveys.

questionnaires.

interviews.

case studies.

participant and non-participant observation.

observational trials.

studies using the delphi method.

by using  production possibilities graph.  opportunity costs are key expenses in financial matters and are utilized as a part of registering money saving advantage investigation of a venture. such expenses, be that as it may, are not recorded in the record books but rather are perceived in basic leadership by processing the money costs and their subsequent benefit or misfortune.

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