What role do transaction fees play in a blockchain network?

Transaction fees play a crucial role in a blockchain network primarily by incentivizing network validators, also known as miners in proof-of-work systems or validators in proof-of-stake systems. These fees act as a reward for the effort and computational resources expended by these participants to maintain and secure the network. When transactions are processed, validators compete to add new blocks to the blockchain, and fees associated with those transactions provide them with a financial incentive to prioritize processing transactions and validate blocks accurately.

In a decentralized network, these transaction fees ensure that there is a motivation to keep the network running efficiently and securely. Additionally, they help to deter spam transactions since users would need to pay fees for every transaction they send, thereby disincentivizing misuse of the network.

The other statements do not accurately reflect the true role of transaction fees. Funding central authority expenses is not applicable in a decentralized context, as blockchains typically do not have a central authority. Limiting the number of transactions is not a primary purpose of transaction fees; instead, they may help prioritize transactions during high demand. Lastly, it is incorrect to state that fees are optional and have no impact, as they are essential for the economic model of maintaining a healthy and incentivized network.