Which of the following is an example of an affirmative covenant? $(1)$ Borrower may not sell fixed assets in excess of $$25,000$ without the bank's prior written consent. $(2)$ Borrower must maintain casualty insurance on the bank's collateral at all times. $(3)$ Owners' compensation may not exceed $$200,000$ per year. $(4)$ Borrower is prohibited from taking on any additional debt in excess of $$50,000$ without the bank's prior written consent.