Final answer:
A landscaper can move 12 loads of mulch per hour accounting for the 12-minute break he needs to take after every hour of work.
Step-by-step explanation:
The capacity of the landscaper in terms of wheelbarrow loads per hour must take into account both the time taken to load and move one wheelbarrow of mulch as well as the break time. Since the landscaper can move one wheelbarrow in 4 minutes, we can calculate the number of loads moved in one hour (60 minutes). Without breaks, the number would be 60 / 4 = 15 loads. However, since the landscaper has to take a 12-minute break after every hour of work, the actual working time is 60 - 12 = 48 minutes.
During these 48 minutes, the number of loads the landscaper can move is 48 / 4 = 12 loads per hour. So, the correct answer to how many loads per hour the landscaper can move is 12, which corresponds to option c.