Answer:
B. However.
Step-by-step explanation:
The word that reasonably adds meaning to the given sentences would be "however" which means "in spite of"(as per the context of the statement). The first sentence describes the little puppy's dogged urge to go out. While the next sentence contradicts this and elaborates that it had been taken out but due to the scorching heat, it wished to come inside promptly. Thus, the word "however" would be most useful and relevant to add meaning and essence to these statements.