Final answer:
The correct answer to the fill-in-the-blank question is 'b) erratic,' which accurately describes a manner of working that is unpredictable and inconsistent, opposing good job performance.
Step-by-step explanation:
You are not going to do well in your job if you continue to work in such a(n) erratic and desultory manner. The correct answer is b) erratic. This sentence is describing a manner of working that is unpredictable and inconsistent, which could hinder job performance. Diligent would imply careful and steady work, which is a positive trait. Lethargic would imply a lack of energy or enthusiasm, which could also make sense in this context, but it does not pair as well with 'desultory' as 'erratic' does. Lastly, systematic would imply a methodical and organized approach, which would likely lead to good job performance, making it an incorrect choice in this sentence.