Ya bro both are correct but both are not related to each other so option is b

Assertion: The RBI supervises the functioning of formal sources loans in India.
Reason: RBI is authorised to issue currency notes.

Explanation:
The Reserve Bank of India (RBI) is the central banking institution of India and is responsible for the supervision and regulation of the banking sector in the country. It plays a crucial role in managing the monetary policy and ensuring the stability of the financial system.

Supervision of Formal Sources of Loans:
- The RBI acts as the regulator and supervisor of the formal sources of loans in India, which include commercial banks, cooperative banks, and non-banking financial companies (NBFCs).
- It formulates and implements various regulations and guidelines for these institutions to ensure the smooth functioning of the lending activities and to safeguard the interests of depositors and borrowers.
- The RBI monitors the operations of these institutions, including their lending practices, interest rates, provisioning norms, and asset quality, to maintain a healthy and stable banking system.
- It conducts regular inspections, audits, and reviews to assess the financial soundness and compliance of these institutions with the prescribed norms and regulations.
- The RBI also issues guidelines on priority sector lending, which mandates a certain percentage of loans to be extended to sectors such as agriculture, small-scale industries, education, and housing, among others.

Authorization to Issue Currency Notes:
- The RBI is the sole authority responsible for issuing and managing the currency in India.
- It has the exclusive right to issue currency notes of various denominations, including the design, security features, and circulation of these notes.
- The RBI ensures an adequate supply of currency in the economy and maintains its integrity by preventing counterfeiting and ensuring the genuineness of the currency in circulation.

Correlation between Assertion and Reason:
- The reason provided in the assertion is that the RBI is authorized to issue currency notes. While this statement is true, it alone does not explain why the RBI supervises the functioning of formal sources of loans.
- The correlation between the assertion and reason is that the RBI's authority to issue currency notes gives it a significant role in regulating the banking sector and overseeing the formal sources of loans in India.
- The RBI's supervision of the formal sources of loans is not solely based on its authority to issue currency notes but also on its broader responsibilities as the central bank of the country.

Conclusion:
Based on the explanation provided above, it can be concluded that both the assertion and reason are true, but the reason alone is not the correct explanation of the assertion. Hence, option 'B' is the correct answer.