Final answer:
Calvin is tense and nervous when he enters the Murry's house for the first time.
Step-by-step explanation:
The best answer choice that describes Calvin when he enters the Murry's house for the first time is He is tense and nervous because he's in a new place. This is evident in the book 'A Wrinkle in Time' by Madeleine L'Engle, when Calvin visits the Murry's house for the first time. He is unfamiliar with the surroundings and feels a sense of unease and nervousness.
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