Observe the relationship between first two words and then fill the suitable word/words at the fourth place.
Levitt : Malate hypothesis :: Steward : ......................

Explanation

To solve the analogy question, we need to analyze the relationship between the first two words and then apply that relationship to find the suitable word for the fourth place.

1. **Identify the relationship**: The first pair of words is "Levitt" and "Malate hypothesis." Levitt is a scientist known for proposing the Malate hypothesis, which explains the role of malate in plant turgor pressure and the functioning of guard cells in stomata.

2. **Identify the second pair**: The second word in the pair is "Steward." We need to find out what hypothesis Steward is associated with, similar to how Levitt is associated with the Malate hypothesis.

3. **Recall Steward's contribution**: Steward is known for the "starch-sugar hypothesis." This hypothesis describes the relationship between starch (stored food) and sugar (current food) in plants, particularly in relation to their role in the functioning of guard cells and the opening and closing of stomata.

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