10 millimoles of a diacidic base exactly neutralises 100ml of an acid. Then the Normality of that acid is

A diacidic base of 10 millimoles can neutralise a dibasic acid of 10 millimoles or a monobasic acid of 20 moles.
In 100ml of dibasic acid solution, 10 millimoles are present.
∴ The normality is 0.2N and the molarity is 0.1M.
A monobasic acid solution has 20mm in 100ml.
∴ The normality is 0.2N and the molarity is 0.2M.

Hence the answer is (A) 0.2M.