He used to------early. ?

The correct choice for the sentence "He used to ------ early." is B) "get up." This is because the phrase "used to" followed by a verb is indicative of a habitual action or state in the past. The structure requires the base form of the verb without any additional conjugation or auxiliary verbs.

In English, "used to" is specifically used to express something that was regularly true or a familiar routine in the past but may no longer occur. For example, "He used to get up early" indicates that getting up early was a regular practice for him in the past.

Let's examine the other options:

- A) "gets up" is incorrect because it is in the present tense and does not match the past habitual context set by "used to."
- C) "getting up" is the gerund form, which cannot stand alone in this structure without an auxiliary verb like "is" or "was."
- D) "got up" uses the simple past tense, which contradicts the habitual nuance of "used to."

Thus, "get up" is the appropriate choice, completing the sentence correctly to convey the intended meaning.