Translation:There are pictures on the fridges, in which there are many apples.
Since I first wrote that question 7 months ago, I've seen many examples of "az a ... , amelyik/ami/etc" translated to "the ... , which ..." The reason is that in English you don't need a demonstrative adjective (those fridges) to point out which fridges you mean, because the second half of the sentence (after "which" or "that") points it out. So to do it twice sounds redundant. But I'm talking only about English. In Hungarian you do need the "az a ..., amelyik/etc" construction.