Final answer:
The primary sector has been decreasing in Atlantic Canada. With economic development, there is a trend away from primary sector jobs to those in the secondary, tertiary, and quaternary sectors, the latter of which would include software developers.
Step-by-step explanation:
The sector in Atlantic Canada that has been decreasing is the primary sector. This is because, in accordance with Clark's Sector Model, with industrialization and economic development, the primary sector commonly declines. This sector involves the extraction and production of raw materials, which has seen a reduction in employment and production as economies evolve. As economies develop further, employment shifts to the secondary sector, and more significantly, to the tertiary sector and quaternary sector, which include services, and the production of ideas and information respectively.
A software developer, according to the economic sectors, would be categorized within the quaternary sector. This sector is focused on ideas, including new technologies, information management, and advanced education and arts. The quaternary sector has grown, particularly with the rise of information technology and high-tech jobs since around 1970, marking the integral role of the information revolution in all industries.
Answer: A. Primary Sector