Latest explanation for closure of stomata is

Which of the following theory gives the latest explanation for closure of stomata?

Which of the following theory gives the latest explanation for closure of stomata?

Which of the following theories gives the latest explanation for closure of stomata?

Which of the following theory gives the latest explanation for closure of stomata?

Which of the following theory gives the latest explanation for the closure of stomata

A phytohormone, responsible for closure of stomata is

A phytohormone, responsible for closure of stomata is (a) Ethylene (b) ABA (c) Auxin (d) Gibberellin

Assertion : According to Scarth, opening and closure of stomata is controlled by pH value. Reason : Low pH value favours opening of stomata and higher pH value closure of stomata.