The Classic Trade-Off Between Guns and Butter Refers To

The classic trade-off between guns and butter refers to:

A) The fact that if we spend money on national defence we won't spend money on social welfare
B) The fact that government welfare reduces the incentive for people to work
C) The more we spend on national defence, the more we will be able to produce commodities
D) The more we spend on national defence, the less we can spend on personal goods