This Reasoning Strategy Is Commonly Used in High Performing Countries

This reasoning strategy is commonly used in high performing countries and takes advantage of student's knowledge of combinations.Identify the equation that represents this strategy.

A) 15 - 8,think 10 + 5 - 8,take from the 10: 10 - 8,add back on the 5 to get the answer.
B) 14 - 8,take away 4 to get to 10,then take away 4 more to get the answer.
C) 12 - 5,it takes 5 to get to 10 and 2 more to 12 and 5 + 2 = to get to the answer.
D) 7 + 6,5 + 2 is seven and 6 is 5 + 1,add 5 + 5 and add the 2 and 1 to get the answer.