Answer:
Error by commission
Explanation:
The two accounts in the question are receivables so that they are of the same class. Thus, crediting Messrs Y.K. Grace and co's account instead of Mr. O.I. Felix is an error by commission.
Error by commission is an error that do not require a suspense account to correct it because it does not affect the trial balance. To correct this error, debit Messrs Y.K. Grace and co's account by the same amount, then credit Mr. O.I. Felix's account by the said amount.
