The chemical prescribed by a doctor in treatment of infectious diseases are called
Antibiotics
The explanation for the correct option:
(C)Antibiotics: Are used to treat or prevent some bacterial infections so the doctor prescribed the antibiotics.
The explanation for the incorrect option:
(A) Antigens: These are the substance which is capable of stimulating an immune response, in general, there is two main division of antigens are recognised foreign antigens and auto-antigens.
(B) Lotions: It is used to maintain hydration of skin for keeping skin healthy and soft.
(D) Creams: These help to protect against moisture loss, which makes them ideal for the treatment of rashes and dry skins.
Thus, The correct option is (c) antibiotics.