Alex received a four-year scholarship to State U. that covered tuition and fees, room and board, and books and supplies. If Alex becomes a full-time student, then:

A.the opportunity cost of attending State U. includes the sum of the benefits Alex would had from attending each of the other schools to which he was admitted.

B.the opportunity cost of attending State U. includes the money Alex could have earned working for four years.

C.attending State U. for four years is costless for Alex.

D.Alex has no incentive to study hard while at State U.

正确答案：the opportunity cost of attending State U. includes the money Alex could have earned working for four years.