Fill in the blanks with the most appropriate word.
If I _____ taller, I _____ be a policeman, but I'm too short.
This sentence talks about the second conditional that is used to express imaginary and impossible situations. So, second conditional uses forms of verbs in past tense. The structure of second conditional is: “If” clause (if + subject + simple past verb) followed by Main clause ( subject + would + verb). Hence, Option C is the correct answer here. Options A and D cannot be used as they use forms of verbs in present tense. Option B cannot be used as it would render the sentence grammatically incorrect.