What do you understand about futures?
An option on futures is an option on 1 futures contract.
One CL (Light Crude Oil) futures contract controls 1,000 Barrels.
For every $0.01 of the price of the option, it costs $10.00
So, for a July CL option that costs $20.00, you pay $20,000.
To find contract specs you can google - commodity contract specifications