The correct option is D Gibberellin
Barley endosperm test is a bioassay for gibberellin. Nicholis and Paleg used barley endosperm for gibberellin bioassay. In this, Barley grains are cut in half along their equatorial axis. The embryo halves are discarded and the remaining endosperm halves are grouped into two lots. One serves as a control and the other lot is treated with the test solution (gibberellin containing). Endosperm halves in presence of GA show high amylase activity and production of reducing sugars.