What is the main characteristic of a permissioned blockchain?

A permissioned blockchain is defined by its access control features, where entry to the network is limited to authorized participants only. This means that only individuals or entities that have been granted permissions can join the network and participate in the transactions. This characteristic is pivotal in maintaining privacy, security, and control over the data and the membership of the blockchain.

In contrast, the other characteristics presented in the choices indicate different blockchain types. The option stating that anyone can join the network describes a public blockchain, which allows unrestricted participation. The mention of operating with a native cryptocurrency is common in many blockchains but does not apply specifically to permissioned blockchains, as they may not rely on such currency for operations. Lastly, a definition that states it is solely for public use again aligns with a public blockchain context, which is contrary to the essence of permissioned blockchains. Thus, the focus on having restricted access for participants distinctly characterizes permissioned blockchains.