The correct answer is: C. Increase or decrease
An account is a record of the increases and decreases in an item. The balance of an account is the difference between the increases and decreases. The balance can increase or decrease, depending on whether the increases are greater than the decreases or vice versa.
Option A is incorrect because an account can also record decreases in the balance of an item.
Option B is incorrect because an account can also record increases in the balance of an item.
Option D is incorrect because appreciation is an increase in the value of an asset, not an increase or decrease in the balance of an account.