Answer: Direct investment in cryptocurrencies

**Explanation:** - **Option A (Correct):** Direct investment in cryptocurrencies involves owning the digital assets outright, which necessitates the use of a cryptocurrency wallet. This wallet stores the public and private keys required to access and manage the assets on a blockchain. - **Option B (Incorrect):** ETFs that replicate digital asset returns typically use derivatives or other financial instruments rather than holding the actual cryptocurrencies. As a result, investors do not need a cryptocurrency wallet. - **Option C (Incorrect):** Cryptocurrency trusts allow investors to trade shares representing pooled holdings of a cryptocurrency. Since the trust manages the underlying assets, individual investors do not require a wallet or encryption keys.

Author: LeetQuiz Editorial Team