Final answer:
Tornadoes in the United States are most commonly seen during April, May, and June, which align with the peak of severe weather conditions in 'tornado alley.'
Step-by-step explanation:
In the United States, tornadoes are most common during the spring to early summer months. The answer to the question 'During which months are tornadoes most common in the United States?' is (b) April, May, June. This period is when the necessary atmospheric conditions, such as warm, moist air from the Gulf of Mexico, collide with cooler, drier air from the north and west, which creates instability and the potential for severe thunderstorms and tornadoes. Additionally, the central United States, known as tornado alley, is the most active part of the world for tornadoes.
Tornadoes are most common in the United States during (b) April, May, June. This period, commonly known as tornado season, is when the conditions are most favorable for the formation of tornadoes. During these months, warm, moist air from the Gulf of Mexico clashes with cold, dry air from the north, creating a perfect environment for tornadoes to develop.