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

Physiological factors are indeed a key component in understanding the susceptibility of aquatic plants to selective herbicides. These factors refer to the internal biological processes and characteristics of the plants themselves, such as their growth stage, metabolic pathways, and specific leaf morphology. Different species of aquatic plants may respond variably to herbicides based on their physiological makeup. For instance, younger plants or those in a rapid growth phase may absorb and metabolize herbicides differently compared to mature or dormant plants. Additionally, the plant's cellular structure can determine how well it can penetrate the herbicide, influencing the overall efficacy of the application.

While environmental conditions, application equipment, and herbicide history are relevant factors in the overall effectiveness of herbicide application and management strategies, they do not specifically pertain to the innate biological traits that directly influence a plant's susceptibility to herbicides. Environmental conditions can certainly affect herbicide performance, application equipment is necessary for application but does not impact plant biology, and herbicide history relates to previous exposures or resistances developed by the plant, neither of which directly address the physiological characteristics intrinsic to the plants themselves.