Answer: A. 10% of the time, the population parameter will lie outside of the interval.
Step-by-step explanation:
If we have confidence interval is that we are certain that it contains the true population parameter in it.
Similarly , if we have a 90% confidence interval for a population parameter, then we are 90% certain that it contains the true population parameter in it.
i.e. 10% not certain that it contains the true population parameter in it.
i.e. 10% of the time, the population parameter will lie outside of the interval.