At the last minute, Amidu backed … of the plan.

Analyze the question: This tests phrasal verbs with "back". We need the particle that fits "backed ___ of the plan".

Explain the concept: The phrasal verb "back out of" means to withdraw from an agreement, promise, or plan one had earlier committed to. It is always followed by "of".

Other phrasal verbs with "back":

• back up = support or reverse (e.g., back up a file, back someone up)
• back off = retreat or move away (not followed by "of" in this sense)
• back down = give up a claim or position in an argument (followed by "from", not "of")

Step-by-step solution:

1. The sentence has the structure "backed ___ of the plan", so the particle must be followed by "of".
2. Test each option: • "backed up of the plan" is wrong. • "backed off of the plan" is not standard English. "Back off" is informal, and Standard English does not use "of" after it. • "backed out of the plan" is correct. It means he withdrew from the plan. • "backed down of the plan" is wrong. We say "backed down from".
3. "At the last minute" also fits the idea of withdrawing from a plan just before it was carried out.

Answer: C. out

Tip: Remember the fixed phrase "back out of" (a plan, deal, or promise). If "of" follows the blank, think "out of". Phrasal verbs are a regular feature of WASSCE Lexis and Structure, so learn them in whole phrases rather than as single words.