What does this sentence (on ability to broadcast a valid transaction and transfer balance) mean? Here is the article.

"The Bitcoin blockchain records every event throughout Bitcoin's history—new coins and evidence of transfers—back to 2009 when the network started," said Valkenburgh. "Every computer on the network also has to be running compatible software so that the nodes can see and validate transactions. So, if your software is not compatible or if you fail to meet or invalidate any of the consensus rules baked into the Bitcoin code base, then the network would ignore your transaction. That's all it is to have a Bitcoin: the ability to broadcast a valid transaction and transfer that balance."

What does the bold sentence mean? 

a. If you have a Bitcoin, it means you have the mentioned ability;

b. Only if you have the mentioned ability can you own a Bitcoin.

Does it mean a or b or none of them?
It means both. The power to transfer your Bitcoin to another address is the same as owning a Bitcoin. You can transfer your Bitcoin if and only if you own it.