Chess Opening Theory/1. d4/1...Nf6/2. Nf3/2...d5/3. Bg5/3...e6

=Torre Attack= e6 is the most common response, and a solid, though perhaps insipid move. It does leave the knight pinned, and play into white's plans, leaving e5 as a prime destination for white's knight. Black's will almost certainly have to play Be7 at some point too.

Theory table
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'''1. d4 Nf6 2. Nf3 d5 3. Bg5 e6'''