Final answer:
Acanthosis or callus formation is classified as a secondary lesion because it results from the progression or manipulation of a primary lesion, such as thickened skin due to irritation or pressure.
Step-by-step explanation:
The level of response of Acanthosis/Callus is a B. Secondary lesion. A secondary lesion is the result of the progression or manipulation of a primary lesion. Acanthosis refers to thickening of the skin, which is often a response to irritation or pressure, making it a secondary lesion, much like a callus that forms due to repeated friction or pressure. Secondary lesions can also include conditions like rashes or scarring.