For a rotating column of air connected to a storm cloud to be
considered a tornado, it must do
which of the following?
A. reach speeds of at least 300 kilometers per
hour
B. last for over 15 minutes
C. make contact with the ground
D. occur during the day

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes