Many Plants Produce Tannins to Reduce Herbivory, but Tannins Are

Many plants produce tannins to reduce herbivory, but tannins are not toxic when ingested. In what way do tannins make plants unpalatable to herbivores?

A) Tannins bind to the gut walls of herbivores, inhibiting nutrient uptake.
B) Tannins disrupt the osmotic gradient in the digestive tract, causing ingested tissue to be flushed through the herbivores gut before nutrition can be extracted.
C) Tannins neutralise the pH of the herbivores gut, thereby preventing gastric juices from degrading the plant material.
D) Tannins denature the gut enzymes of the herbivores, preventing breakdown of the plant material.
E) Tannins combine with proteins in leaves, producing a high indigestible compound.