Opportunity cost is the fee you pay for withdrawing money from a retirement account investing in a variety of types of investments to minimize risk the difference between a chosen investment and one that is passed up the cost an individual pays for buying and selling stock

the difference between a chosen investment and one that is passed up

Explanation:

im pretty sure its this one because it makes sense that an oppertunity can be passed up

c.

worked constantly and gave many sincere speeches about the importance of independence

a)scientists

explanation:

the national defense education act had two main goals. the first one was to provide personal that was oriented to defense, including scholars, engineering students and so on. the other goal was to provide financial assistance for the students who would be enrolling at colleges and universities in the 1960s.