June 2012 Q1

Hello, In appendix iii) in the answers to question 1, the black-scholes model is used to price the option of being able to develop a follow on product "within 2 years". So in the black-scholes equation T=2, and Pa is provided assuming positive cash flows begin in year 3. But I'm a bit confused because if the option is to start "within" 2 years, then can't T be less than 2? And if the company chose to start development in year 1, then positive cash flows would start in year 2 which would mean Pa would be greater because there is less discounting? Or am I missing a reason why the follow on product can't be developed until year 2? Thanks, Stu