<span> Hello, this is just a matter of terms.
Compare and contrast Future perfect, present perfect and past perfect.
Past perfect means the action occurred before another action and it is also in the past.
Hope that helped! Let me know if you need any other help or need further explanation! :)
</span>
Answer:
C. The scientist's conclusion is flawed because the number of hours of sunlight changed and, therefore, the experiment is not controlled.
Explanation:
A controlled experiment is an experiment used to test a single variable at a time. The variable that is being tested is called the independent variable, and it is directly manipulated by a scientist. The rest of the variables need to remain unchanged in order not to get wrong results like the scientist in the given scenario.
As the scientist is trying to see how gamma rays affect marigolds, only the gamma ray exposure is supposed to change throughout the experiment. The amount of water remained the same, but the number of hours of sunlight didn't. That's why we don't know what exactly affected the growth of marigolds - the sunlight or the gamma rays? And that's why the scientist's conclusion is flawed.
"objective; object of preposition" Is your answer.
It is a warning that indicates a future event.
