The questions from this lot which could be tested in a scientific manner would be "what causes some people to be color-blind"
and
"what are the best shoes to wear when exercising"
Both of these questions can be tested in a scientific way through an experiment.
Visual aids are tools that help to make an issue or lesson clearer or easier to understand and know (pictures, models, charts, maps, videos, slides, real objects etc.). ... Visual aids are those devices which are used in classrooms to encourage students learning process and make it easier and interesting.
I believe the answer is A
The answer is d because you have to make sure that everything is right
