Answer:
A. costly.
Explanation:
The word marginal means costly in the field of economics. In general, the meaning of marginal is small, tiny and low. Marginal refers to the focus on the cost on the product or profit that is earned from selling of that product. Companies use marginal analysis as a tool in order to help them maximizing their profits so here in the sentence marginal refers to the cost.
B, goods can move freely between countries since there are no obstacles in the way of free trade between nations
The answer is behavior inhibition in which a student with ADHD who has trouble waiting his turn, repelling distractions, delaying instant gratification, or disturbing a faulty line of thinking is suffering this effect. In addition, allow the use of the calculator is an example of an accommodation or strategy that teachers may use to adapt to the needs of students with ADHD. As stated, the accommodation addresses academic skills.
Another name for the enlightenment era is the age of reason.