Maximum float

 Q: Sponsor wants the project completed in 40 days.

The CPI is 1.1 , the project critical path duration is 38 days with a standard deviation of 2 days. What is the maximum project float?
 
A. 8 days
B. 2 days
C. 4 days
D. 0 days
 
Please point out the correct answer with explanation.

 the answer is D.

Float on Critical path is 0..no float allowed. CPI is related to cost not schedule so just ignore that.