Choose the correct variant. He always ___ the house at 6 a.m.

The sentence describes a habitual action that occurs every day at 6 a.m. The word 'always' indicates a routine. For a third-person singular subject ('He'), the present simple tense requires the verb to be in its '-s' form. Therefore, 'leaves' is the correct verb form to complete the sentence, indicating a regular occurrence. The other options are incorrect: 'will leave' is future tense, 'left' is past tense, and 'leave' is the base form or present tense for plural subjects or 'I/you'.