Select the word or phrase that makes this sentence grammatically correct: The child's fever was too high for him to lie comfortably in bed.

The word "to" is a preposition used to indicate direction, place, or position. In this sentence, using "to" would not convey the intended meaning of excess; instead, it would create confusion, as it does not appropriately modify the adverbial phrase that describes the child's condition.

While "much" can also indicate a large degree, it is typically used in negative constructions or questions. In this sentence, "much" would not fit grammatically and would alter the intended meaning regarding the severity of the fever, making it sound awkward and incorrect.

The word "more" is a comparative adverb used to indicate a greater degree of something. However, in this context, it does not properly convey the sense of excess necessary for the sentence. Saying the fever was "more high" would be grammatically incorrect and does not align with standard English usage.