Information in the environment that causes an animal to react is

A stimulus

Explanation:

When a physical or chemical change occurs either in the internal system of an organism or in the surrounding environment of the organism and this change is detectable by the sensory system of the organism then this change is called as Stimulus. The ability due to which the organism reacts towards this change is known as sensitivity of the organism. The reaction of the organism in relation to the stimulus is known as response.