Final answer:
When hot moist conditions are added to itchy skin, such as in eczema, the itching is likely to increase due to the summation effect. Moisturizing creams can help alleviate symptoms by hydrating the skin.
Step-by-step explanation:
The question asks about the threshold of itch and the summation effect when hot moist skin is involved, which might lead to an increase in itching. In the context of eczema, which is an allergic reaction, hot moist conditions are likely to aggravate itching due to increased skin sensitivity and potential irritation. Since the term 'summate' implies that the effects add up, when hot moisture is added to already itchy skin, it's reasonable to expect that the itching could increase due to a cumulative effect.
Moisturizing creams are commonly used to manage symptoms of conditions like eczema. These creams typically contain emollients, which help to soften and soothe the skin, as well as occlusives and humectants, which help to retain moisture. The inflammation and dry itchy patches characteristic of eczema are addressed with these components, which is why hydrating the skin with a moisturizer is recommended treatment.
If the effects of hot moist skin were to summate, or add together, with the symptoms of eczema or other skin irritations, one might expect that the itching increases (Option C). Moisturizers and treatments like corticosteroid creams and immunosuppressants are used to manage and reduce the intensity of these symptoms by hydrating the skin and reducing inflammation.