Step 1: Understanding the Concept:
This question pertains to the 'Angi Rasa' (dominant sentiment) of the first Sanskrit epic, the 'Ramayana', as established by great critics like Anandavardhana and Vishvanatha.
Step 3: Detailed Explanation:
The assertion (A) states that 'Karuna' is the dominant sentiment of the Ramayana.
In his 'Dhvanyaloka', Anandavardhana explicitly states: "Ramayane hi karuno rasah svayam-adikavina sutritah" (In the Ramayana, the Karuna Rasa has been initiated as the primary sentiment by the first poet himself).
The very origin of the epic is rooted in 'Shoka' (sorrow).
When Valmiki saw one of a pair of 'Krauncha' birds being killed by a hunter, his spontaneous grief manifested as the first 'Shloka' (verse).
This transformation of 'Shoka' (sorrow) into 'Shloka' (poetry) is the foundational aesthetic principle of the Ramayana.
The reason (R) supports this by mentioning the pervasiveness of this sentiment throughout the text.
From the beginning (the Krauncha bird incident), through the middle (the exile of Rama, the death of Dasharatha, the abduction of Sita), to the end (the final separation of Rama and Sita as Sita descends into the earth), the undercurrent of sorrow is constant.
Even when 'Vira' (heroic) deeds like the killing of Ravana take place, they are framed within the context of Rama's suffering and his quest to regain his lost beloved.
The final conclusion of the Valmiki Ramayana is undeniably tragic, reinforcing the claim that Karuna is the 'Angi Rasa'.
Since the continuous presence of sorrow from the start to the end is exactly what makes 'Karuna' the dominant sentiment, Reason (R) provides the logical evidence for Assertion (A).
Step 4: Final Answer:
Both (A) and (R) are true, and (R) correctly explains why (A) is true. Hence, Option (A) is the correct choice.