Option 1 : 55

**Calculation**:

In the given product the number of 5's is less than the number of 2's. Hence the highest power of 10 will be equal to the number of 5's in the expression.

The 5's will come from 5,10, 15, 20 and 25.

Their powers are 21, 16, 11, 6 and 1 respectively.

The total number of 5's in the expression = 21 + 16 + 11 + 6 + 1 = 55

Hence the correct option is **1**.

__Additional Information__

The index of the greatest power (IGP) of a number is the maximum power of that number that divides the original expression.