To increase output in the short run, an artisanal bakery adds units of labour (bakers) to a fixed kitchen workspace and oven facility. The table below shows the relationship between the units of labour employed and the total daily output of sourdough loaves.
| Units of labour | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| Output of loaves | 10 | 24 | 42 | 62 | 80 | 95 | 107 | 116 | 121 | 123 |
At what point does the bakery first begin to experience diminishing marginal returns?
When the 4th unit of labour is employed
When the 5th unit of labour is employed
When the 6th unit of labour is employed
When the 10th unit of labour is employed
