To answer this question, we need to recall the details from the Harry Potter series.
Option A) He catches it with his right hand - This option is incorrect because Harry Potter did not catch his first Snitch with his right hand.
Option B) He catches it with his left hand - This option is incorrect because Harry Potter did not catch his first Snitch with his left hand.
Option C) He catches it in his mouth - This option is correct. In the first Quidditch match he played as the Seeker for the Gryffindor team, Harry Potter caught the Snitch in his mouth. This was an unconventional and daring move that surprised both his teammates and opponents.
Option D) He summons it with "Accio" - This option is incorrect because Harry Potter did not use the spell "Accio" to capture his first Snitch.
Therefore, the correct answer is option C) He catches it in his mouth.