Hot summers and cold winters best define a climate region. a. subarctic b. highlands c. humid continental d. marine west coast

The best answer would be C. Humid Continental.
Areas that are considered humid continental are typically found within the northern and central parts of North America, as well as the north-eastern, north-western, and central parts of Asia.
This season is typically comprised of cold, harsh winters, and warm -> hot summers.

The Subarctic climate is very close, so if it's not Humid Continental I would go with Subarctic.

Don’t use up to much of them it leads to pollution