Based on your description of the scatterplot, the correct response would be:
There are no outliers and one cluster.
You mentioned that there is a loosely packed cluster of data points between 1 to 4.5 hours studied and test grades between 77 and 98, and only one dot is mentioned at 0.5 hours and a grade of 45, which does not seem to be classified as an outlier. Therefore, the characteristics suggest that there is one cluster and no outliers.