Explanation:
100% FDI (Foreign Direct Investment) refers to the investment made by foreign entities in the economy of another country. In this case, the question is asking about the sectors where 100% FDI is allowed. Let's analyze each option:

a) Banking:
- As of now, 100% FDI is not allowed in the banking sector in India.
- The current policy allows a maximum of 74% FDI in private sector banks, subject to certain conditions and regulations.

b) Insurance:
- Until recently, the insurance sector in India allowed a maximum of 49% FDI.
- However, in 2021, the government of India increased the FDI limit in the insurance sector from 49% to 74%.

c) Defence:
- The defence sector in India has specific regulations regarding FDI.
- Under the automatic route, 100% FDI is allowed in the defence sector.
- However, beyond 49%, government approval is required, and it is subject to certain conditions related to national security.

d) None of these:
- This option signifies that none of the given sectors, i.e., banking, insurance, or defence, allow 100% FDI.

Conclusion:
In conclusion, the correct answer to the question is option 'D' - None of these. As of now, none of the given sectors (banking, insurance, defence) allow 100% FDI in India. However, it is important to note that FDI policies can change over time, and it is always advisable to refer to the latest regulations and government notifications for accurate information.