Biological factors that contribute to susceptibility to selective herbicides include which of the following?

Physiological factors are key biological elements that influence a plant's susceptibility to selective herbicides. These factors include the plant's growth stage, the presence of protective traits such as cuticles or trichomes, and metabolic pathways that determine how a plant absorbs, translocates, or detoxifies the herbicide. Understanding these factors is crucial for effectively using selective herbicides, as they dictate how a plant will respond to the herbicide's chemical action.

In contrast, environmental conditions refer to external factors like temperature and humidity that can affect herbicide efficacy but are not directly biological in nature. Application equipment pertains to the technology and methods used to apply herbicides, which can influence delivery and effectiveness but do not directly alter a plant's inherent biological responses. Lastly, herbicide history considers the previous use of herbicides and their potential impact on the current efficacy and resistance patterns, which, while important, do not fall under the biological factors affecting susceptibility.