Answer: C) 7 years
There's not much explanation other than I did an online search for the answer. Many sources I'm finding are saying "up to 7 years", which means that is the longest it will stay on the credit report.
v
Standard the random variable

using the transformation

where

and

are the mean and standard deviation of

, respectively.

Now, you can recall that for any normal distribution, approximately 95% of its data falls within 2 standard deviations of the mean, so to either side, there is approximately 2.5% of data that falls below 2 standard deviations from the mean, and 2.5% that falls

above

. In other words,

.