Concept: This question tests knowledge about various aspects of plant morphology, reproduction, and seed structure, specifically focusing on common botanical terms and characteristics of fruits and seeds.

Why (D) is correct: The outermost layer of the endosperm in maize (and other cereals) is called the aleurone layer. This layer is rich in proteins and enzymes, which are crucial for the germination of the seed. It secretes enzymes like $\alpha$-amylase that digest the stored starch in the endosperm, making nutrients available to the embryo.

Why other options are wrong:

• (A) A sterile pistil is called a staminode: A sterile pistil is called a pistillode. A staminode is a sterile stamen.
• (B) The seed in grasses is not endospermic: The seed in grasses (e.g., maize, wheat, rice) is typically endospermic, meaning the endosperm persists and stores food for the embryo.
• (C) Mango is a parthenocarpic fruit: Mango is a drupe, a fleshy fruit with a stony endocarp. It is not parthenocarpic; it develops after fertilization. Parthenocarpic fruits develop without fertilization (e.g., banana).

Common Mistake: Students often confuse staminode and pistillode, or misremember which fruits are parthenocarpic.

NEET Tip: Remember that monocot seeds (like grasses) are generally endospermic, while many dicot seeds (like beans) are non-endospermic (food stored in cotyledons).

Correct Answer: (D)