Answer:
D. Tests that run too long risk slowing down the feedback cycle for developers
Explanation:
The reason you should run your unit test suites not to take a long time is that "Tests that run too long risk slowing down the feedback cycle for developers."
Otherwise, the developers would find it difficult to detect problems instantly, causing delay to fix the problems which will eventually delay the developers or project's team to advance to the next stage of the project.
You are usually editing a word document when you are finished typing up and assignment or what not, then highlighting what you want to edit will tell the computer/word document what and where your making your edits.
