The smallest possible value of z is the denominator of the reduced fraction x/y. We note the prime factors of the members of set y are
... 2², 7, 2³, 3²
so if there are any even members of set x, the fraction can be reduced to something divided by 2. The number 6 in set x is even, so we have
... 6z/4 = 6·2/4 = 3 (an integer) when z=2
The lowest possible value of z is ...
... B) 2
