Assertion: Corolla of mustard is described as cruciform.
Reason: Petals of mustard are arranged in diagonal pairs.
Assertion and Reason are correct and Reason correctly explains the Assertion.
Assertion and Reason are correct and Reason does not explain the Assertion.
Assertion is correct but Reason is incorrect
Both Assertion and Reason are incorrect.
Corolla of mustard has four petals arranged in two free diagonal pairs. Hence it is described as cruciform corolla.