Explanation:

- Gift

- A gift is a transfer of property or money done voluntarily without expecting anything in return.

- It is typically a one-sided transaction, not a mutual exchange.

- Sale

- A sale involves transferring ownership of goods or property in exchange for money.

- It typically involves one party giving goods and the other party providing money.

- An Exchange

- This involves mutual transfer of ownership between two parties.

- Both parties give and receive something of value, which can include money or barter.

- It fits the description where neither thing or both things are money.

- None

- This implies that none of the provided options fits the given situation.

- However, this is not applicable here, as "an exchange" suits the description.