Step 1: Understanding the Concept:
This question tests the difference between commonly confused words, specifically 'than' and 'then'.
Step 2: Detailed Explanation:
The sentence is making a comparison between "my job" and "his job".
- than: is a conjunction used for making comparisons. (e.g., "She is taller than her brother.")
- then: is an adverb used to indicate time or sequence. (e.g., "First I will eat, then I will sleep.")
- that: is a conjunction or pronoun used for various purposes, but not for comparison in this context.
- there: is an adverb indicating place.
Since the sentence compares the quality of the job done by "I" and "he", the correct word is "than".
The complete sentence is: "I would have done a better job than he did."
Step 3: Final Answer:
The correct option is (A) because "than" is used to introduce the second element in a comparison.