Step 1: Understanding Assertion.
Social media posts and images do not follow a structured format like tables, so they are examples of unstructured data, not structured data. Hence, Assertion (A) is false.
Step 2: Understanding Reason.
Unstructured data is defined as data that does not follow a predefined format. This statement is correct.
Step 3: Conclusion.
Thus, Assertion (A) is false, but Reason (R) is true.
Final Answer: (C)