Answer:
A. an easy decision for an economist, but a difficult decision for a physicist or a chemist.
Explanation:
Assumption refers to an unconfirmed facts.
Economics is the scientific study of human behavior in relation to ends and scarce means which have alternative uses. A person who studies economics is called an Economist.
Physics is the study of properties and interaction of space, time, matter and energy. A person who Study physics is a physicists.
Chemistry is the study of composition of substances and the changes they undergo as a consequences of alteration in the constituents of their molecules. A person who studies chemistry is called a chemist.
Both physicist and chemist makes use of experiment to deduce a facts. It is difficult for them to assume a facts until experiment has been carried out.
On the other hand, economist usually based their judgement on assumptions. It is very difficult for an economist to carry out an experiment to deduce their fact because they deal with human behavior which is different from person to person.
Based on the definition of assumption above, it can be deduced that Physicist and chemist have confirmed facts from performing experiment while an economist deals with unconfirmed facts.