It's worth looking carefully at the correct answers of official problems to see the kind of thing that GMAT considers acceptable. Here, I agree, that the use of 'whose' seems a little unclear (it could be referring to musicians, Elvis or just Jerry Garcia). However, since there's no alternative we just have to accept it. You could rewrite the whole sentence, or break it up into two sentences, to remedy this.
However, it shows an important point about the use of "wh" words on GMAT. It's a good starting point to think of the rule as "NOUN, which", but that's very often too simplistic. Take this example:
The bowl of apples, which is / are on the table, ...
I'm sure that your instinct takes you very quickly to "is". What's happened here is that we've just slipped in another modifier - 'of apples' - between the noun and the 'which'. Actually, it would be difficult to rewrite the sentence to give the same meaning. Some languages allow you to say 'The of apples bowl, which ...' but that doesn't work in English. It highlights a problem that sentences are essentially a line of words. If we want to pack in lots of modifiers then there's not enough space for all noun modifiers to touch the noun they're modifying. A more accurate rule is that noun modifiers should be as close as possible to the noun they're modifying. Check out SC724 from OG2018 for an example of this.