Thank you very much @Mike9241 for the prompt answer. That exactly answers my question (and I am sure will do the same for many others).
This was a same-day sale of ISO.
My 1099-B does have a value for "Cost or other basis". In my opinion the cost basis is exactly right since that was the cost basis. It feels as if I am twiddling the numbers to make everything come out correctly. Maybe this is just a case of the forms not catching up to requirements for reporting such income on W-2.
I also wish the TurboTax UI would label their input fields with the IRS form line/column/box numbers (where there is a correspondence). That way when people give answers in terms of line/column/box, I can know where to put the numbers on the UI. In this case the box was labeled "Total adjustments to gain (or loss)" on the UI, so it was obvious. Once I complete everything on the UI, I will go back and look at all the forms/schedules to see if it looks right.
