Answer:
Option A) The width of the confidence interval will be narrower.
Step-by-step explanation:
We are given the following in the question:
A student decreases the level of confidence from 95% to 90%, while all other quantities remained unchanged.
The confidence level decreased from 95% to 90%.
Since the confidence level decreases, the corresponding statistic decreases.
This will decrease the marginal error.
Thus, the confidence interval will become narrower.
Option A) The width of the confidence interval will be narrower.