How is alternate phylllotaxis defined?

Question

Three or more leaves per node, the angle of divergence varying
One leaf per node, 137.5 degree angle of divergence between leaves
One leaf per node, and the leaves positioned 180 degrees from each other
Two leaves per node, 90 degrees angle of divergence between leaves
Two leaves per node 45 degree angle of divergence between leaves

Answer 1

Two leaves per node, the angle of divergence varying.