The pronoun "their" is ambiguous: it could mean cleaning supplies, low cost items, or low hazard items. The change to "the use of such household items" should eliminate the ambiguity. However, I've got to be honest and admit that I've read this sentence several times, and I'm still not actually sure what it means. It seems that "comprised of unknown chemicals from polyurethane" is describing "cleaning supplies," in which case the sentence would be saying "Cleaning supplies... exist in low cost items," which doesn't make much sense. And even without the ambiguous pronoun, I'm not quite sure what the "household items" are here. The cleaning supplies? The low cost items? The low hazard items? I'm a little lost as to the meaning of this sentence. Where's it from?

thanks expert
but i must say i am bit confused here....

You said 2nd is better than 1st because it removes the pronoun reference problem.But i think the pronoun reference ambiguity stills exist in B (though i sound better i think at ground level A=B here in terms of pronoun reference)
so how it can be B?

grockit_andrea wrote:The pronoun "their" is ambiguous: it could mean cleaning supplies, low cost items, or low hazard items. The change to "the use of such household items" should eliminate the ambiguity. However, I've got to be honest and admit that I've read this sentence several times, and I'm still not actually sure what it means. It seems that "comprised of unknown chemicals from polyurethane" is describing "cleaning supplies," in which case the sentence would be saying "Cleaning supplies... exist in low cost items," which doesn't make much sense. And even without the ambiguous pronoun, I'm not quite sure what the "household items" are here. The cleaning supplies? The low cost items? The low hazard items? I'm a little lost as to the meaning of this sentence. Where's it from?

Andrea - thanks for the attempt. The source is a website called my-gmat (WinPrep). While B sounded the best, it still had issues as you highlighted.....my issue is how does one train to figure one such answer which may not be the best but the one with "least error" . Does GMAT actually present the best answer which may still have some or the other error?