Answer:
more in Lowland.
Explanation:
Of Highland has more capital per worker then it means that the level of capitalisation of production is higher than in the Lowland.
Due to the law of diminishing returns the highly capitalised economy of the Highland will only have little increase in productivity with additional capital.
However an additional capital input in the Lowland will lead to a larger increase in productivity as this economy is not yet subject to the law of diminishing returns.