Which of the Following Is Thought to Be Necessary for the Development

Multiple Choice

Which of the following is thought to be necessary for the development of a tornado?

A) a $\underline { \text { horizontally } }$ rotating body of air generated by differences in wind speed between low-level and upper-level air flow
B) a strong updraft
C) a mesocyclone
D) all of the above
E) B and C only