Step 1: Understanding the Concept:
The question asks to identify the true statements regarding the nature and content of ancient inscriptions, a primary source for historians.
Step 2: Detailed Explanation:
(A) Routine agricultural practices and events of daily life are the subject-matter of inscriptions: This statement is generally incorrect. Inscriptions were costly to produce and were intended to be permanent records. Therefore, they were typically used to record important matters like royal edicts, donations to temples, land grants, or victories in war, not the mundane events of daily life.
(B) Record the achievements, activities or ideas of those who commissioned them: This is correct. This was the primary purpose of most inscriptions. For example, Ashoka's inscriptions recorded his ideas on Dhamma, and the Prashastis (eulogies) recorded the achievements of kings.
(C) Writings are engraved on hard surfaces such as stone, metal or pottery: This is the definition of an inscription (or epigraph). The use of durable materials ensured their longevity. This statement is correct.
(D) The earliest inscriptions were in Prakrit: This is correct. The earliest substantial body of historical inscriptions in India, the edicts of Emperor Ashoka (3rd century BCE), were composed in various dialects of Prakrit, which was the common language of the people at the time.
Step 3: Final Answer:
Statements (B), (C), and (D) are correct, while statement (A) is incorrect. Therefore, the correct option is (4).