Option B — Turmeric and Litmus
Turmeric and litmus are natural indicators as both are obtained from natural sources (turmeric plant and lichen respectively), unlike methyl orange and phenolphthalein, which are synthetic indicators.
The key distinction is natural vs. synthetic indicators. Litmus (from lichen) and turmeric (from the turmeric plant) are natural indicators. Methyl orange and phenolphthalein are synthetic (man-made) indicators. The textbook (Ch. 2) lists litmus as a natural indicator and uses turmeric as an example of a natural substance that can indicate acids/bases. Eliminate options containing only synthetic indicators.