Which of the Following Error Is an Error of Principle

Multiple Choice

Which of the following error is an error of principle

A) 5,000 received from Sham credited to Ram A/c
B) 5,000 incurred on installation of new plant debited to travelling expenses A/c
C) 500 paid for wages debited to salary A/c
D) 500 being purchase of raw material debited to purchase A/c ` 50