When a person makes a choice, there is always a
a.
cost
b.
regret
c.
benefit
d.
problem

A. cost.

In economics, opportunity cost represents the benefit that a person misses out on when choosing one alternative over another. In every decision we make, there is a cost involved, even when the cost is only the inability of picking another alternative instead.

Opportunity costs are often overlooked, but they are important to consider when making any decision.

the correct answer is the following is a list of inventions made in the medieval islamic world, especially during the "islamic golden age" (8th to 13th centuries),[1][2] as well as the late medieval period, especially in the emirate of granada and the ottoman empire.

science and technology in the islamic world adopted and preserved knowledge and technologies from contemporary and earlier civilizations, including persia, india, china, and greece-roman antiquity, while making a number of improvements and innovations.