Final answer:
Milo is best described as 'Bored' at the beginning of Act 1 in 'The Phantom Tollbooth', showing disinterest and ennui towards his surroundings. The correct answer is option B).
Step-by-step explanation:
The word that best describes Milo at the beginning of Act 1 is B) Bored. In the story The Phantom Tollbooth, Milo is characterized by his lack of interest in the world around him. He is depicted as someone who is disinterested in his surroundings and in the activities he engages in. This sense of ennui and disengagement remains a central theme until he embarks on his fantastical journey.