Final answer:
The largest employment sector in Atlantic Canada is the Tertiary Sector, which offers various services. A software developer falls within the Quaternary Sector, which is part of the broader service sector and focuses on high-tech and IT jobs.
Step-by-step explanation:
The largest employment sector in Atlantic Canada is the Tertiary Sector. The tertiary sector provides a myriad of services, ranging from retail and hospitality to healthcare and education. A software developer, as listed in the question provided, would be part of the Quaternary Sector, which focuses on the management and analysis of data and is recognized for high-tech software and information technology jobs that form an integral part of all other industries.
The shift from primary and secondary sectors to the tertiary and quaternary sectors is indicative of a developing or developed economy. In regions like the United States and Western Europe, and likewise in well-developed areas within Canada including Atlantic Canada, service sector jobs, including those in the quaternary sector, have become dominant, defining the contemporary workforce landscape.