Which of the following are sulpha drugs?

Any member of a group of synthetic antibiotics containing the sulfanilamide molecular structure is known as sulpha drug

or sulfonamide.

Hence according to the definition Sulphapyridine and prontosil must the answer to the question.

Prontosil in the body is converted to sulphanilamide and hence will come under sulpha drugs.

Therefore options (i) and (ii) are correct. Options (iii) and (iv) are incorrect.