Final answer:
Option D 'The professor and the students are all ready for the weekend' is the grammatically correct sentence.
Step-by-step explanation:
The sentence that is grammatically correct is option D: The professor and the students are all ready for the weekend.
In this sentence, the subject 'The professor and the students' agrees with the verb 'are', which is the correct plural form. The sentence is also complete and coherent, expressing readiness for the weekend.
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