The mass extinction at the end of the Mesozoic Era was caused by ______. a. solar radiation c. an ice age b. a meteor or asteroid colliding with Earth d. volcanic activity

The answer to the question stated above is letter b. a meteor or asteroid colliding with Earth
The mass extinction at the end of the Mesozoic Era was caused by a meteor or asteroid colliding with Earth. This was said to happen about 65 million years ago.