Read these lines: "Over time, Pavlov observed that the dogs began to salivate not only at the taste of food, but also at the sight of food, at the sight of an empty food bowl, and even at the sound of the laboratory assistants' footsteps. Salivating to food in the mouth is reflexive, so no learning is involved. However, dogs don't naturally salivate at the sight of an empty bowl or the sound of footsteps." According to the quoted lines, why was salivating at footsteps notable while salivating at food was not?

1. The quoted lines state that salivating to food in the mouth is reflexive, so no learning is involved there. 2. They also state that dogs do not naturally salivate at an empty bowl or at footsteps. 3. A response that is not natural must have come from somewhere else, which is what made it stand out, option A. 4. Nothing in the quoted lines mentions the dogs' age, the loudness of the footsteps, or which response came first, ruling out the rest. _Source: OpenStax Psychology 1e (CC BY 4.0), Ch 6 "Learning", section 6.2 Classical Conditioning_