of which mainstream audiences have rarely seen 
(ROOT (SBAR (WHPP (IN of) (WHNP (WDT which))) (S (NP (JJ mainstream) (NNS audiences)) (VP (VBP have) (ADVP (RB rarely)) (VP (VBN seen))))))
(ROOT (SBAR (WHPP (IN ) (WHNP (WDT ))) (S (NP (JJ ) (NNS )) (VP (VBP ) (ADVP (RB )) (VP (VBN ))))))