To solve this problem we need to find arithmetic mean of the given prize values.
To find arithmetic mean of any series of numbers you simply add them all together and then divide them by the number of numbers in the series.
We can express this by following formula:

Where

represents value of each number in the series.
In this problem, we have 10000 numbers. Most of them are zero because most tickets don't win anything.
We just add the value of all prizes and divide them by the number of tickets.

The answer is C. Your expected payoff is $1.2.