When actual loss is . . . . . . . . than the estimated loss, the difference between the two is considered to be abnormal gain.

Option A is incorrect because it says that actual loss is more than the estimated loss. This would result in an abnormal loss, not an abnormal gain.

Option B is incorrect because it says that actual loss is equal to the estimated loss. This would not result in an abnormal gain or loss.

Option C is incorrect because it says that actual loss is higher than the estimated loss. This would result in an abnormal loss, not an abnormal gain.