Concept:
Assertion-Reason type questions require checking:
• Whether Assertion is factually correct
• Whether Reason is factually correct
• Whether Reason correctly explains Assertion
Step 1: Analyze Assertion (A).
Punjab flock is indeed classified as a dual-purpose breed.
This means:
• It is used for both egg production and meat production
• Such breeds are economically valuable in poultry farming
\[
\text{Hence, Assertion (A) is correct.}
\]
Step 2: Analyze Reason (R).
The reason states that it has a large body size but poor egg-laying ability.
This statement is incorrect because:
• Dual-purpose breeds are expected to have moderate to good egg-laying ability
• They also have reasonable body size for meat
• If egg-laying were poor, it would not be classified as dual-purpose
\[
\text{Hence, Reason (R) is incorrect.}
\]
Step 3: Check logical connection.
Since Reason is incorrect, it cannot explain the Assertion.
Step 4: Final conclusion.
\[
\boxed{\text{Assertion is correct but Reason is incorrect}}
\]
\[
\boxed{(3)}
\]