I have been asked this question during an online exam.
My query is from Immunological Preparations in section Immunological Preparations of Drug Biotechnology
For explanation: DPT (also DTP and DTwP) is a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus. A combination vaccine is one which can provide immunogenicity to more than one type of disease. Some more examples of recombination vaccines are DTaP, Hep-B.