Concept: This question tests your understanding of different types of root systems, specifically distinguishing between adventitious roots and the primary root system.

Why (D) is correct: Adventitious roots are defined as roots that develop from any part of the plant body other than the radicle. This can include stems, leaves, or even branches. Examples include prop roots of banyan, stilt roots of maize, and fibrous roots of monocots.

Why other options are wrong:

• (A) radicle: Roots developing from the radicle form the primary root system (e.g., taproot system).
• (B) plumule: The plumule develops into the shoot system (stem, leaves, flowers).
• (C) primary root: The primary root is the direct continuation of the radicle and is part of the normal root system, not an adventitious root.

Common Mistake: Students often confuse the origin of different root types. Remember that the radicle gives rise to the primary root, while adventitious roots originate elsewhere.

NEET Tip / Mnemonic: Think of "Adventitious" as "additional" or "arising from unusual places" – not the usual radicle.

Correct Answer: (D)