In classical Indian philosophy, the statement that the world is God made manifest and that the divine is the very soul within oneself can most clearly be traced to which group of sacred texts?

Introduction / Context:
Indian religious literature develops from hymns and rituals towards more abstract spiritual and philosophical reflection. The insight that the world is a manifestation of the divine and that the same divine reality is identical with the inner self is a landmark of this evolution. This question asks you to identify which group of texts most clearly expresses this non dual vision that equates the individual self with ultimate reality.

Given Data / Assumptions:

• The key idea is that the world is God manifest and that God is the inner soul.
• The options list different kinds of Sanskrit texts: Vedic Samhitas, Upanishads, Puranas and law codes.
• We assume standard school level understanding of which texts focus on ritual and which develop philosophical ideas.

Concept / Approach:
The Upanishads are often called Vedanta or the end of the Vedas, both in a textual and philosophical sense. They move beyond ritual action and speak of Brahman, the ultimate reality, and Atman, the inner self. Many famous Upanishad passages teach that Atman and Brahman are essentially one, and that the world is a manifestation of this one reality. The correct option must therefore point to the Upanishads rather than to hymn collections, narrative myths or law books.

Step-by-Step Solution:
Step 1: Identify the core idea in the quoted statement as a non dual equation between God, world and self. Step 2: Recall that Upanishad texts such as Chandogya and Brihadaranyaka analyse the relation between Atman and Brahman. Step 3: Note that Vedic Samhitas like the Rig Veda concentrate more on hymns to deities and ritual praise. Step 4: Recognise that Puranas and Manusmriti focus on stories, rituals, law and social duties rather than on abstract metaphysics. Step 5: Select the option that directly names the Upanishads as the source of this philosophical essence, which is option B.

Verification / Alternative check:
A quick verification is to recall famous Upanishad formulas such as Tat tvam asi which means that ultimate reality and the self are one, or Aham Brahmasmi which affirms the identity of the individual self with Brahman. These statements mirror very closely the idea that God is the soul within and that the world is divine manifestation. No other group of texts in the options expresses this teaching as centrally and systematically as the Upanishads do.

Why Other Options Are Wrong:
Option A, the early Vedic Samhitas, contain lofty hymns but they usually address multiple deities in a ritual context. Option C, the Puranas, present stories about gods, goddesses and cosmic cycles but do not primarily teach non dual philosophy. Option D, Manusmriti, lays down social codes and laws for different groups in society. Option E refers to later yoga commentaries, which are important but not the classical source for the doctrine that world and self are identical with God.

Common Pitfalls:
Students sometimes assume that any spiritual sounding idea must come from the Vedas in general, without distinguishing between Samhitas, Brahmanas and Upanishads. Another pitfall is to think that Puranas, because they narrate stories of gods, are the main philosophical texts. To avoid confusion, always remember that the Upanishads are the central texts for deep metaphysical and non dual teachings in the Hindu tradition.

Final Answer:
The philosophical essence that the world is God manifest and that God is one own soul can most clearly be traced to the Upanishads that expound non dual spiritual philosophy.