Which question could be tested in a scientific manner?
what causes some people to be color-blind?
why should people be nice to other people?
why is the color purple better than the color red?
what are the best shoes to wear when exercising

What causes some people to be color-blind?

That is a question that can be tested using the scientific method.

The correct answer is option A which is, "What causes some people to be color-blind?"

Explanation:The tested in scientific manners means doing experiments and devise an answer by interpreting the result on the bases of scientific studies.In testing the cause of color blindness, we may check genetics of color blind people and then answer it.But in all other options, we are questing about the psychological and emotional questions of people which can not be tested on the basis of scientific experiments.

Ithink that b is correct but just in case wait to see if someone else answers