Which of the following is natural acid-base indicator?

I. Litmus

II. Turmeric

Both I and II

The correct answer is option 4. Both I and II.

The natural acid-base indicator among the given options is: Both I and II.

Both Litmus (I) and Turmeric (II) are natural substances that can act as acid-base indicators. Litmus turns red under acidic conditions and blue under basic conditions. Turmeric changes its color from yellow to red in acidic solutions and from yellow to brown in basic solutions.