Assertion (A) : Endosperm is completely consumed during the development of embryo in ex-albuminous seeds.

Reason (R) : Castor, pea and beans are all examples of ex-albuminous seeds.

The correct option is: Assertion (A) is true, but Reason (R) is false.

Let us analyze both the Assertion and the Reason step-by-step to understand why this option is correct.

1. Analysis of Assertion (A):
Seeds can be classified into two main types based on the presence or absence of endosperm in the mature seed:
• Non-endospermic or ex-albuminous seeds: In these seeds, the endosperm is completely consumed by the developing embryo during its growth before the seed matures. The food is then stored in the cotyledons. Examples include pea, gram, and beans.
• Endospermic or albuminous seeds: In these seeds, a portion of the endosperm remains in the mature seed as it is not completely consumed during embryo development. Examples include wheat, maize, barley, and castor.
Since the endosperm is completely consumed in ex-albuminous seeds during embryo development, Assertion (A) is true.

2. Analysis of Reason (R):
The Reason statement claims that castor, pea, and beans are all examples of ex-albuminous seeds.
• Pea and beans are indeed ex-albuminous (non-endospermic) seeds.
• However, castor is a classic example of an albuminous (endospermic) seed, where the endosperm persists in the mature seed to nourish the germinating seedling.
Because castor is not an ex-albuminous seed, the statement in Reason (R) is false.

Conclusion:
Since Assertion (A) is correct and Reason (R) is incorrect, the assertion is true but the reason is false.