Find the Number of Standard Deviations from the Mean

Find the number of standard deviations from the mean. Round your answer to two decimal places.
-The number of hours per day a college student spends on homework has a mean of 4 hours and a standard deviation of 0.75 hours. Yesterday she spent 3 hours on homework. How many standard deviations from the mean is that?

A) 1.33 standard deviations below the mean
B) 0.67 standard deviations above the mean
C) 0.67 standard deviations below the mean
D) 1.33 standard deviations above the mean