Final answer:
The correct answer is 'Had'. This makes the sentence 'He had not dinner at 8 PM', which expresses the past tense in negative form. It's an example of the Past Simple tense in English Grammar.
Step-by-step explanation:
The correct answer to fill in the given sentence would be option A 'Had'. The sentence becomes 'He had not dinner at 8 PM'. The auxiliary verb 'had' in this case is used to express the past tense in negative form, which indicates something that didn't happen or wasn't the case in the past. As such, this is also an example of the usage of the Past Simple tense in English language grammar.
Learn more about Past Simple tense