The correct answer is A. Clerical error.
A clerical error is an error made in the process of recording or processing financial information. It is a mistake that is made by the person who is recording the information, and it is not an error in the underlying principle or concept.
In this case, the machinery was purchased for Rs. 10000, but it was wrongly debited to the purchases account. This is a clerical error because it is a mistake that was made in the process of recording the purchase. The underlying principle or concept of the transaction is correct, but the error was made in recording the amount.
B. Error of principle is an error that is made in the application of accounting principles. It is a mistake that is made in the way that the financial information is recorded or reported.
C. Compensating error is an error that occurs when two errors offset each other. This means that the overall effect of the two errors is zero.
D. None of these is not the correct answer because it does not describe the error that was made.