Final answer:
The monthly costs of two Azure virtual machines using the B2S size vary depending on their usage, with factors such as data transfer and operational hours influencing the cost.
Step-by-step explanation:
If two Azure virtual machines use the B2S size, their monthly costs will largely be influenced by how they are used. Answer option b) Costs vary depending on usage is correct. Factors such as the amount of data transfer, any additional features or services utilized, and how many hours the machines are running, will all impact the final cost. While the subscription type might influence overall pricing structures or offer certain discounts, the virtual machines themselves incur costs based on usage. Therefore, different usage patterns will result in variable costs even if the machines are the same size.