Final answer:
Option (b) is correct because both the assertion and the reason are true, but the reason isn't the correct explanation for the assertion since not all plants possess autotrophic nutrition—some are heterotrophic and lack chlorophyll.
Step-by-step explanation:
The correct answer to the question regarding the autotrophic mode of nutrition in plants and the presence of the green pigment chlorophyll is option (b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. While it is true that most autotrophic plants contain chlorophyll, which allows them to perform photosynthesis and synthesize their own food, the assertion that all plants possess autotrophic nutrition is false. This is because there are some heterotrophic plants, such as holo-parasitic plants, that lack chlorophyll and are unable to produce their own food, relying on other organisms for nutrients.