 Following C. S. Holling, functional responses are generally classified into three types, which are called Holling's type I, II, and III.Type I functional response assumes a linear increase in intake rate with food density, either for all food densities, or only for food densities up to a maximum, beyond which the intake rate is constant.The linear increase assumes that the time needed by the consumer to process a food item is negligible, or that consuming food does not interfere with searching for food.