How is a node selected to run Smart Contract in Ethereum A node that runs a smart contract will be paid with GAS. How is this node selected? I guess this node should be trustworthy. Or multiple nodes are running the same smart contract just to make sure somehow?
A node that runs a smart contract will be paid with GAS.


This is incorrect. The miner who mines the block containing the transaction interacting with a contract is the one who is paid with ETH, which is gas consumed * gas price.


  How is this node selected? 


Through the mining process.


  Or multiple nodes are running the same smart contract just to make sure somehow?


Even after the block is mined, every node on the network that receives it will independently validate the contract execution. If the miner lies about the outcome of the execution, the block will be deemed invalid.