Final answer:
The three industries important to Ontario's economy today are mining, tourism, and automobile manufacturing, reflecting a combination of both traditional and modern economic sectors.
Step-by-step explanation:
Ontario's economy today is bolstered by several key sectors. While the primary economic sector activities like agriculture, forestry, fishing, and mining are important, Ontario has seen significant shifts toward manufacturing and services. Automobile manufacturing in Ontario is one of Canada's most significant economic sectors due to the province's historical strength in the auto industry and its strategic location near the US border.
Tourism in Ontario is also a major industry, with attractions such as Niagara Falls, Toronto's urban landscape, and its numerous festivals contributing significantly to the economy. The service sector in Ontario is thriving too, and it employs a large portion of the workforce. This sector encompasses education, healthcare, finance, real estate, and professional services, highlighting the province's shift towards a knowledge-based economy.
Given this information, the correct answer to the student's question is B. Mining, tourism, and automobile manufacturing are three industries that are important to Ontario's economy today.