In legumes, it has been shown that "sleep" (nastic) ...

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In legumes, it has been shown that "sleep" (nastic) movements are correlated with
A) positive thigmotropisms.
B) rhythmic opening and closing of K+ channels in motor cell membranes.
C) senescence (the aging process in plants).
D) flowering and fruit development.
E) ABA-stimulated closing of guard cells caused by loss of K+.

[clippers!]

I chose B and got the answer, hope that helps.