You have all the math worked out that you need to, the question makes the answer quite difficult to figure out.
If you split up the question into 2 parts it may make more sense.
You have the second half of the question figured out. (the product of a positive multiple of 5 and an even number)
The first half asks how many positive integers are less than 60.
answer? 59. 1,2,3,4,5,6 etc...
How many of those positive integers are equal to the product of a positive multiple of 5 and an even number?
(60 doesn't count, the first part asks for numbers less than 60)
Thus, the answer is B. (5)