Certified Bitcoin Professional Practice Exam

The accurate number of bitcoins currently in circulation is a dynamic figure that changes over time due to the mining process. As of late 2023, the total number of mined bitcoins closely aligns with the figure stated in option B, 18,591,868.75.

Bitcoin has a capped supply of 21 million coins that will ever be mined, and new bitcoins are generated as rewards for miners who validate and add transactions to the blockchain. This reward is halved approximately every four years in an event known as 'halving,' which slows down the rate at which new bitcoins are introduced into circulation.

The figure mentioned reflects the bitcoin supply as it stands after accounting for these mining rewards and taking into consideration the fact that some bitcoins may be lost or rendered inaccessible. Therefore, option B captures the current state accurately, whereas the other options either underestimate or overestimate the total number of bitcoins in circulation.