Which one of the following is the most striking effect of...

Gibberellins are plant growth regulators that promote internodal elongation. Their most striking and characteristic effect is the reversal of dwarfism in many genetically dwarf plants, such as dwarf pea and maize. When gibberellins are applied to these genotypically dwarf plants, they undergo rapid stem elongation and become phenotypically tall, indistinguishable from normal tall varieties.

Answer: Conversion of genotypic dwarf plants into phenotypic tall plants.