Step 1: Understanding the Concept:
'Karaṇa' is the fifth limb of the Pañcāṅga. 'Viṣṭi' is the seventh of the movable Karaṇas. In astrological terminology, Viṣṭi is synonymous with 'Bhadrā'.
Step 2: Detailed Explanation:
Analysis of Assertion (A):
In Muhurta scriptures, it is clearly stated: "Viṣṭi-bhadrā saṃjñā" (Vishti is named Bhadra). Bhadra is the name of the daughter of the Sun God, and she is considered fierce. Whenever the Vishti Karana arrives, it is called 'Bhadra'. Thus, Assertion (A) is true.
Analysis of Reason (R):
The reason provides the application: because Vishti is Bhadra, the duration of its occurrence is called 'Bhadra Kala'. This time is avoided for auspicious ceremonies because Bhadra is believed to devour the results of good work. This statement is the direct consequence and the technical explanation of why Vishti and Bhadra are equated in assertion A. It defines the temporal aspect of the nomenclature.
Evaluating the Relationship:
The assertion gives the name; the reason explains what that name represents in terms of time (Kāla). They are perfectly linked in a causal-explanatory relationship.
Step 3: Final Answer:
Both are true and R is the correct explanation of A.