According to the criteria of essentiality proposed by Arnon and Stout, which of the following conditions must be met for an element to be considered essential for plant growth? 1. The plant cannot complete its life cycle or set seeds in the absence of the element. 2. The requirement of the element must be specific and not replaceable by another element. 3. The element must be directly involved in the metabolism of the plant. Select the correct option:

Options:

• A: 1 and 2 only
• B: 2 and 3 only
• C: 1 and 3 only
• D: 1, 2 and 3

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