Why do economists measure the cost or money price of things when opportunity cost is what we actually are considering when we deciding whether or not to purchase?

answer; /// the only one thats make little sense is (c) fair credit billing act;

"harry t. moore (1905-1951) – civil rights activist, leader, and the first martyr of the civil rights movement. fannie lou hamer (1917–1977) – leader in the american civil rights movement; co-founder of the national women's political caucus and freedom democratic party. james farmer (1920–1999) – congress of racial equality."