According to Steward`s starch hydrolysis theory, which one of the following is the principal reason for the opening of stomata during daytime?
Photosynthetic utilization of CO2 in guard cells.
Influx of K+ ions into guard cells under the influence of ABA hormone.
Conversion of sugar into starch in guard cells.
Efflux of K+ ions from guard cells under the influence of ABA hormone.