Explanation:

- Option 1: Zero

- This suggests that money has no utility, which is incorrect as money is a medium of exchange and value.

- Option 2: Less than one

- This implies low utility but does not truly reflect money's ability to command goods and services.

- Option 3: More than one

- This could imply high utility, but it does not align with a balanced utility per unit cost approach.

- Option 4: One

- The law of equi-marginal utility often considers the price of money as one, indicating the baseline or standard unit of utility measurement against which other utilities are compared.

- Correct Answer: Option 4 is correct as it represents money as a stable unit of account for measuring utility.