Elektryczność=electricity and prąd (elektryczny)=(electric) current are two completely different terms, although the words are interchangeable in some contexts in colloquial speech. I wouldn't accept them as interchangeable translations in this course but in this sentence you could use both. I guess prąd would be a more natural thing to say here.
I found the pick-one-from-three pictures for "electricity", of which I had to pick "prąd" because the other two words were words which I already knew, were very confusing. One seemed to be a stream running through a cellar with pillars (a byzantine cistern perhaps) and the other seemed to be a drawing board with a few drawing instruments.
I have yet to do an exercise with the actual word "prąd" in it......