Step 1: Understanding the Concept:
This question is based on the Pashpashahnika (the introductory chapter) of Patanjali's Mahabhashya, which is the definitive commentary on Panini's grammar. Patanjali discusses the 'Prayojana' or the reasons for studying grammar (Vyakarana), which is one of the six Vedangas. He lists five primary reasons: Raksha (Protection), Uha (Modification/Contextual adjustment), Agama (Scripture/Tradition), Laghu (Economy/Brevity), and Asandeha (Removal of doubt).
Step 2: Detailed Explanation:
The Assertion (A) states that grammar must be studied for the protection (Raksha) of the Vedas. Patanjali argues that the Vedas must be preserved in their pristine form, with correct pronunciation and grammatical integrity. Without the knowledge of grammar, one might mispronounce or misinterpret the Vedic texts, leading to their eventual decay or corruption. Thus, Vyakarana acts as the 'guardian' of the sacred word.
The Reason (R) introduces the concept of Uha. In Vedic rituals (Yajnas), a mantra often needs to be modified to suit the specific context of the ritual. For example, if a mantra originally addresses one deity in the singular but the current ritual involves multiple deities, the priest must change the gender or number of the words in the mantra. Patanjali explicitly states: "na khalu sarvairliṅgairna ca sarvābhirvibha-ktibhirvede mantrā nigaditāḥ" (Mantras are not explicitly mentioned in the Vedas with all genders and all case endings). A person who does not know grammar cannot perform these modifications (Uha) correctly.
Therefore, since the protection of the Vedas (Raksha) includes their correct application in rituals, and correct application depends on the ability to modify them (Uha), the Reason (R) directly supports and explains the necessity mentioned in Assertion (A). Grammar is the tool that ensures the Vedas are both preserved and correctly applied through logical modification. Both statements are accurate traditional tenets of the Vyakarana school.
Step 3: Final Answer:
Both statements are correct, and the need for modification (Uha) is a sub-component of why grammar protects (Raksha) the functional integrity of the Veda. Thus, (A) is the correct choice.