I would also add an option "I don't know" or "I don't care"
For many people it is going to be a true statement.
For instance I use the cheapest broker for my purposes (global macro) so whatever the commission are I will pay them. As long as I make money who gives a **** if you lose a bit on slippage, bid/offer, commissions, hardware, software, broadband, Bloomberg or anything else....
Of course I have a good idea what I really spend for each of above - however I do not think the knowledge of that means anything - unless you want to start your own brokerage .