Correct option is C
Given:
Let's define all the options:
Option A: Mathematics, Sociology, English
Mathematics is a science subject.
Sociology and English are arts/social science subjects.
Mix of different fields.
Option B: Political Science, Sanskrit, Geography
Political Science and Geography are social sciences.
Sanskrit is a language.
Mix of different fields.
Option C: Physics, Chemistry, Biology
All three are pure science subjects.
This is the only group where all subjects belong to the same field (science).
Option D: French, Biochemistry, Economics
French is a language.
Biochemistry is a science subject.
Economics is a social science.
Mix of different fields.
Thus, the correct odd one out is Physics, Chemistry, Biology (because it's the only group where all subjects belong to the same category, while others are mixed).
Thus, the correct option is (c) Physics, Chemistry, Biology.