your cousin works at her desktop computer for prolonged period of time every day. she would like to minimize the harmful effects of such repetitive work. her workspace should be designed with in mind.

 Ergonomics

Explanation:

Ergonomics is the factor that is related with workplace of an individual while designing it. Workplace ergonomics is used for creating working environment by considering factors like abilities,drawbacks, requirements etc of worker.This helps in eliminating the risk and harm of workplace and results in improving the performance and outcomes of the worker by considering every factor of worker ans respective workplace.According to the situation in question,cousin's workplace should be designed in respect to ergonomics so that harmful effect can be reduced.

It should be b i believe

You aren't giving enough information. what kind of "tool" do you mean? if you want an opinion, then jeremy should use a computer to show how his web will look like.