What is the basic mechanism by which growth regulators kill plants?

Growth regulators function primarily by altering the hormonal balance within the plant, which in turn affects various physiological processes necessary for growth and development. These substances can mimic or inhibit natural plant hormones, leading to a disruption in the plant's normal growth patterns.

Specifically, growth regulators can affect processes such as cell division and elongation, leading to stunted growth or abnormal development. By interfering with the synthesis and action of growth hormones, they can induce responses such as premature leaf drop, flowering, or even lead to cell death in certain tissues. This hormonal imbalance, combined with changes in protein synthesis, can ultimately lead to the demise of the plant.

The other options do not accurately reflect how growth regulators operate in relation to plant death, as they focus on different processes such as water absorption, nutrient uptake, and photosynthesis, which are not the primary mechanisms through which growth regulators exert their toxic effects.