Step 1: Understanding the Concept:
This question tests the correct usage of phrasal verbs starting with the verb "back."
A phrasal verb is a combination of a verb and a preposition or adverb that creates a unique meaning different from the original verb.
Step 2: Detailed Explanation:
Let us analyze the meaning of each phrasal verb in the options:
- Option (A) Backed out: "To back out" of something (like a deal, agreement, or promise) means to withdraw from a commitment before it is completed. This perfectly fits the context of losing confidence and leaving a business deal at the last minute.
- Option (B) Backed on: This is not a standard English phrasal verb and has no meaning in this context.
- Option (C) Backed down: "To back down" means to withdraw a claim, demand, or opinion in the face of opposition or to concede defeat in an argument (e.g., "The government backed down on the new tax"). It is not used for withdrawing from business transactions.
- Option (D) Backed onto: "To back onto" means to have the back of something face toward another thing (e.g., "Our house backs onto a park"). This is geographically descriptive and does not fit the sentence.
Thus, "backed out" is the only phrasal verb that is both grammatically correct and contextually appropriate.
Step 3: Final Answer:
The correct option is (A).