What happens if a miner tries to create more new bitcoin than allowed?
Correct answer
Answer B: Nodes applying those rules reject the block as invalid.
Quick explanation
A miner can propose a block but cannot force anyone to accept it. Nodes check whether the new issuance follows the rules they themselves run.
Detailed explanation
The 21-million rule is not guarded by one company or a secret server. Full nodes store and verify the blockchain independently. This includes checking that the coinbase transaction claims no more than the allowed block subsidy and included fees.
A miner can technically try to publish a block with additional issuance. Rule-following nodes would reject it as invalid, however. Computing power alone therefore cannot bypass the supply rule.
Software code can in principle be copied and changed. What matters is which rules users, businesses and other participants voluntarily run and economically recognize. If one group accepted a larger supply while others kept the existing rules, separate networks could emerge. The change would not automatically be Bitcoin for everyone.
Protection thus rests on transparent software, independent validation and distributed choice of rules. It is neither a law of nature nor a central institution's guarantee. Its stability depends on participants continuing to check and accept the existing rule.
Example or everyday application
A miner publishes a block with an excessive coinbase payout. A rule-following full node detects the violation and does not include the block in its valid blockchain.
Common misconception
People often assume miners or developers can change the money supply alone.
What the sources support
The ECB shows with cash that counterfeit or invalid units do not become valid merely by being passed on. In Bitcoin, full nodes perform rule-based validation: a block subsidy above the permitted amount makes the block invalid.