If You Were Comparing Circadian Oscillator Structures Between Plant Species

If you were comparing circadian oscillator structures between plant species, where might you predict that there would be the greatest differences?

A) between tropical orchids and arctic tundra wildflowers
B) between east and west coast cereal crops grown at the same latitude
C) between spring onion plants from the northern and southern hemisphere grown at the same distances away from the equator (each measured at their spring growth optimum)
D) between plants in a garden grown in either a sunny or a shady spot