Explanation:

Let’s break it down:

- The quote “Money is a pivot around which the whole economy clusters” comes from Ralph George Hawtrey.

Option 4: Hawtrey is correct.

Here's what you need to know about the options:

- Keynes: Famous for his work on how government spending influences the whole economy. He talked a lot about money, but this isn’t his line.

- Robertson: Known for his work in monetary economics, but this quote doesn’t come from him either.

- Marshall: Big on supply and demand, marginal utility, and consumer surplus. He helped build the foundations of microeconomics, not quite money in this sense.

- Hawtrey: Focused on money and credit. He described money as central, a kind of axis around which the economy organizes—that’s where this quote comes from.

In a nutshell, the quote is about how money shapes everything else in the economy. Hawtrey nailed that idea.