Scientific experiments must be able to be repeated by multiple scientists to verify the results that are obtained. which of the following is an example of a scientific question that could be used to create an easily reproducible experiment?
a.
why do people like to watch television?
b.
does the mass of a rocket affect the distance it can travel?
c.
what makes the sky blue?
d.
does sugar or salt have a greater effect on plant growth?

d.  Does sugar or salt have a greater effect on plant growth?

Explanation:

Scientific question is the one which can be answered by using a scientific experiment that is included in the scientific methodology. This question can be tested by many scientists depending upon the repetition of the scientific experimental procedure. The scientific experiment is done to determine the cause and effect relationship.

The sugar or salt are the two variables the effect of which can be observed on another variable that is the plant growth. This relationship can be examined by the experimentation process which can be easily repeated by scientists.  

Hence, d.  Does sugar or salt have a greater effect on plant growth? is an example of a scientific question that could be used to create an easily reproducible experiment.