The cattle were . . . . . . . . in the field.

The correct answer is A. grazing.

Grazing is the act of feeding on growing plants, especially grass. Cattle are herbivores, which means they eat plants. They are ruminants, which means they have a four-chambered stomach that helps them digest their food. Cattle are often seen grazing in fields, where they eat grass and other plants.

The other options are incorrect because they do not describe the action of cattle eating grass. Option B, grazed, is the past tense of graze. Option C, will grazing, is the future tense of graze. Option D, none, is not a complete sentence.