Answer:
reduce the balance.
Step-by-step explanation:
Contra account is the opposite account to the given account.
Here, we are discussing asset account. As we know, assets have a debit balance for example: Plant & Machinery Account.
Now, contra to this can be accumulated depreciation account, which carries a credit balance as this will have a decreasing effect on value of Plant and Machinery.
Thus, a contra account will reduce the balance of relative plant asset.
Correct option is
b) reduce the balance.