All of the Following Are True About Proportional Reasoning Except

All of the following are true about proportional reasoning except for :

A) proportional reasoning involves understanding how quantities vary in relation to each other.
B) proportional reasoning is an overarching principle of all mathematics and is central to all sub disciplines of mathematics.
C) proportional reasoning is structurally an additive relationship.
D) proportional reasoning is one of the most difficult topics for children to learn in mathematics.