Explanation:
DPT vaccine is a combined vaccine that is given to children to develop immunity against three diseases- tetanus, diphtheria, and pertussis.

Tetanus:
Tetanus is a serious bacterial infection that affects the nervous system and causes muscle stiffness and spasms, particularly in the jaw and neck muscles, which can make it difficult to breathe and swallow. It is caused by the bacterium Clostridium tetani, which enters the body through wounds, cuts, and puncture wounds. The tetanus vaccine is given to prevent this disease.

Diphtheria:
Diphtheria is a bacterial infection that can cause a thick coating to form in the back of the throat, which can lead to breathing difficulties, heart failure, paralysis, and even death in severe cases. Diphtheria bacteria are spread through coughing and sneezing. The diphtheria vaccine is given to prevent this disease.

Pertussis:
Pertussis, also known as whooping cough, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It is characterized by severe coughing spells that can last for several weeks or more. Pertussis can be particularly dangerous for infants and young children, and can lead to hospitalization and even death. The pertussis vaccine is given to prevent this disease.

DPT Vaccine:
The DPT vaccine contains a combination of three vaccines- a vaccine against tetanus (T), a vaccine against diphtheria (D), and a vaccine against pertussis (P). The vaccine is usually given to infants and young children in a series of doses, typically starting at 2 months of age and continuing until the child is 6 years old. The vaccine helps to build immunity to all three diseases, and is an important part of routine childhood immunizations.

D) All of these