Final answer:
The product that comes in cream, oil, and powder form and is used on the scalp is hair serum, which is designed to nourish and improve hair health.
Step-by-step explanation:
The substance that can be available in cream, oil, and sometimes powder, and can be used on the scalp are often hair care products. However, among the options provided, the correct answer is hair serum. Hair serums are designed to nourish and improve the health of hair and are often found in various forms including cream, oil, and sometimes powder. These products are meant to be applied to the scalp or hair to address a variety of hair concerns such as frizz, dryness, and damage. Hair dye and hair bleach are typically in cream or powder form but not commonly found as oils, and hair mousse is typically found in foam form.