What Is the Most Simplistic Strategy for Adding/counting

Multiple Choice

What is the most simplistic strategy for adding/counting?

A) simultaneously extending the number of fingers on one hand that corresponds to one number to added, and doing the same with the second hand concerning the second number to be added
B) counting by extending one finger for each item and then counting the total number of fingers extended on each hand
C) counting in your head after looking at a picture of the items
D) counting in your head without using a concrete example