Final answer:
The best replacement for 'tempo' in the given sentence is 'pace' because it refers to the rate of activity or progress, fitting the context of a workplace.
Step-by-step explanation:
The best replacement for the underlined word 'tempo' in the sentence "The tempo of his new job was much quicker than that of his old job." is 'pace'. Options b 'speed' and c 'pattern' could be relevant in other contexts, but a 'pace' is more specifically about the rate of activity or progress in an environment such as a workplace. The word pace as a synonym relates closely to tempo in terms of the rhythm or speed at which something happens over a period, such as the day-to-day tasks at a job.