Answer: a. Both supply and demand.
Explanation:
Lobsters are plentiful and easy to catch in august but scarce and difficult to catch in November. This means that the supply of Lobsters increases in the month of August than in any other month.
At the same time, vacationers shift the demand for lobsters further to the right in august than in any other month. This means that demand for lobsters increases in the month of august than in any other month.
Thus, both supply and demand for lobsters is high in the month of August.