Final answer:
Miners receive 12.5 new Bitcoins when they solve the puzzle first in Bitcoin mining.
Step-by-step explanation:
The correct answer is a) 12.5. Currently, miners receive 12.5 new Bitcoins when they succeed in solving the lottery puzzle first. This is part of the Bitcoin mining process, which involves solving complex mathematical problems to validate transactions on the blockchain. As a reward for their computational work, miners are given a certain number of new Bitcoins.