The price of one share of ABC Company decreased a total of $45.75 in 5 days. What was the average change of the price of one share per day?

To find the average change per day, divide the total change by the number of days:

Average change per day = Total change / Number of days

In this case, the total change is $45.75 and the number of days is 5:

Average change per day = $45.75 / 5 = $9.15

Therefore, the correct option is D. The share decreased $9.15 each day.