In a private school, there were five teachers. Abi and Geetha were teaching French and English. Harini and Geetha were teaching English and Science. Diva and Abi were teaching Maths and French. Hema and Geetha were teaching Social Science and French. Which subject is taught by the maximum number of teachers?

Let's list the subjects taught by each teacher based on the given information:
Abi: French, English, Maths

Geetha: French, English, Science, Social Science

Harini: English, Science

Diva: Maths, French

Hema: Social Science, French

Now, let's count how many teachers teach each subject:

French: Abi, Geetha, Diva, Hema ⟹4 teachers

English: Abi, Geetha, Harini ⟹3 teachers

Science: Geetha, Harini ⟹2 teachers

Maths: Diva, Abi ⟹2 teachers

Social Science: Geetha, Hema ⟹2 teachers

Thus, French is taught by the maximum number of teachers (4).