Concept: This question tests your understanding of the various factors that contribute to seed dormancy, a crucial survival mechanism for plants.

Why (D) is correct: All the listed factors contribute to seed dormancy. An impermeable and hard seed coat prevents water and oxygen uptake, which are essential for germination. The presence of chemical inhibitors (like abscisic acid, phenolic acids, coumarin, etc.) within the seed or seed coat actively suppresses germination. Lastly, an immature embryo means the embryo is not yet fully developed to support germination, requiring a period of maturation before it can sprout.

Why other options are wrong:

• (A) Impermeable and hard seed coat: This is one reason, but not the only one.
• (B) Presence of chemical inhibitors: This is another valid reason, but not exhaustive.
• (C) Immature embryos: This is also a correct reason, but incomplete on its own.

NEET Tip: Remember that seed dormancy is an adaptive feature that ensures seeds germinate only under favorable conditions, increasing the chances of seedling survival.

Correct Answer: (D)