The correct answer is - b. Many jobs on the islands have seasonal ups and downs.
The Caribbean islands have tropical climate, and they are islands that experience summer throughout all of the year. Because of this, the two main branches that bring in the most of the money in the economy, agriculture and tourism, are active throughout the whole year, thus people have work for the whole year without any significant fluctuations. Tourists come throughout all of the year, and the agriculture is active throughout all of the year as well with managing to produce twice or three times per year.