The correct answer is: B. Errors of commission.
Errors of commission are errors that occur when a transaction is recorded incorrectly. In this case, the purchase invoice was entered in the purchase book at Rs. 1,520, which is Rs. 270 more than the actual amount of Rs. 1,250. This is an error of commission because the amount recorded is higher than the actual amount.
Errors of omission are errors that occur when a transaction is not recorded at all. For example, if a purchase invoice is received but not recorded in the purchase book, this would be an error of omission.
Errors of principle are errors that occur when a transaction is recorded using the wrong accounting principle. For example, if a purchase invoice is recorded as a purchase of inventory when it should be recorded as a purchase of equipment, this would be an error of principle.
Compensatory errors are errors that occur when two or more errors offset each other, resulting in the correct overall balance. For example, if a purchase invoice is recorded for Rs. 1,520 but the payment is made for Rs. 1,250, this would be a compensatory error.
Errors of duplication are errors that occur when a transaction is recorded twice. For example, if a purchase invoice is recorded in the purchase book and then recorded again in the cash book, this would be an error of duplication.