Answer:
Internal validity.
Explanation:
Internal validity is the study in which trust relationship is build between treatment and outcome. This relationship is known as <em>cause-and-effect. </em>
In this type research, the studies are based on whether the finding is questionable or not. The research which can overrule the possibility of alternative explanations of our findings is internally valid.
The threats of internal valid study are:
- <u>Natural Improvement </u>
- <u>Maturation</u>
- <u>Historical Events</u>
- <u>Placebo effects</u>
- <u>Nonspecific effects</u>.
So, the correct answer is 'Internal validity'.
Muhmmad ture defeated sonni baru on <span>on 18 February 1493.</span>
<span>Drunk drivers kill two to four times more people than aggressive drivers. This is FALSE. It is the aggressive drivers.</span>
D. It did not allow for a centralized government