The correct answer is Option 4: Renminbi.

The Special Drawing Rights (SDR) is an international reserve asset created by the International Monetary Fund (IMF) to supplement the existing official reserves of member countries. The SDR is based on a basket of major currencies, which currently includes the US dollar, euro, Japanese yen, British pound, and since 2016, the Chinese yuan (also known as the renminbi).

In 2021, there have been no proposals to add any new currency to the basket of IMF`s SDR. However, in the past, the Chinese renminbi was proposed and subsequently added to the basket in 2015, which was a significant milestone for the Chinese currency as it became the first emerging market currency to be included in the SDR basket.

The inclusion of the renminbi in the SDR basket was a reflection of the growing importance of the Chinese economy in the global financial system. It also provided China with a higher international status, as it joined the ranks of the US dollar, euro, Japanese yen, and British pound, which are the other major currencies that make up the SDR basket.

The IMF reviews the composition of the SDR basket every five years to ensure that it reflects the relative importance of currencies in the international monetary system. Therefore, it is possible that in the future, other currencies such as the Indian rupee or South African rand, could be considered for inclusion in the SDR basket. However, there has been no recent proposal for adding any new currency to the basket.

In conclusion, the correct answer to the question is Option 4: Renminbi, which has already been added to the basket of IMF`s SDR in 2015, and there have been no recent proposals to add any new currency to the basket.