Feb 17 (Reuters) - Melvin Capital Management Chief Executive Gabriel Plotkin, Robinhood Markets CEO Vladimir Tenev and Keith Gill, a YouTube streamer known as Roaring Kitty, laid out their defense ahead of a grilling on Thursday by lawmakers over the Reddit-fueled rally in retailer GameStop Corp. (bit.ly/3pucdNd) (Reporting by Niket Nishant in Bengaluru; Editing by Arun Koyyur)