This question asks for the landmark case that defines fraud in the context of contract law.
Derry v.
Peek is the foundational English case that defines fraudulent misrepresentation (fraud).
The court held that fraud is proved when a false representation has been made (1) knowingly, or (2) without belief in its truth, or (3) recklessly, careless whether it be true or false.
This established a high bar for proving fraud.
The other cases deal with different principles: \textit{Lalman Shukla} with communication of offer, \textit{Carlill v.
Carbolic Smoke Ball} with general offers, and \textit{Satyabrata Ghose} with the doctrine of frustration.
Therefore, \textit{Derry v.
Peek} is the landmark case on fraud.