Answer: The answer is (b) Mary increased both assets and liabilities.
Step-by-step explanation: Given that Mary is going to buy a boat worth $30,000 with the help of a loan but she had $2000 cash to put down.
As a result, Mary took the loan for $28,000 to buy the boat. This will add one more number to the number of Mary's assets and also add one more number to the number of liabilities Mary has.
Therefore, after this purchase, the number of assets and the number of liabilities will both increase for Mary.
Thus, the correct option is (b) Mary increased both assets and liabilities.