Which of the following statements, BEST describes the conditions that cause thunderstorms and tornadoes? a. Cool, moist air rises to meet cool, dry air.
b. Warm, moist air rises to meet cool, dry air.
c. Warm, dry air rises to meet cool, moist air.

B - when the warm, moist air and the cool, dry air meet, they create instability in the atmosphere

Your answer is d. silli hope this ! : ) i left an explanation down below if you need it: a sill forms when hot magma squeezes between layers of rock to form a hardened sheet of rock. a sill is basically a tabular sheet intrusion between old layers of sedimentary rock, volcanic beds, or in the direction of foliation inherent in metamorphic rock. the word sill means a concordant intrusive sheet.