The answer is: C.Consider saving money instead of spending it
From that sentence, Benjamin Franklin basically equalize reducing your spending and allocating it to saving as an increase in earning.
Let's take a look at this scenario:
1. You work to earn 100$ on first day, spend $50 on the second day, and work to earn 50$ on the third day. At the end of the the third day, you will have 100$ left.
2. You work to earn 100$ on first day, not spending anything on second day. And choose not to work on third day. At the and of the third day, you will have 100$ left.
From those scenarios, we can see that allocating your spending to spending eventually ending up with similar amount with spending and acquiring additional earning.