The relation between internal energy \[U\], pressure \[P\] and volume \[V\] of a gas in an adiabatic process is \[U=a+bPV\] where a and b are constants. What is the effective value of adiabatic constant\[\gamma \]?

• A. \[\frac{a}{b}\]             
• B. \[\frac{b+1}{b}\]
• C. \[\frac{a+1}{a}\]         
• D. \[\frac{b}{a}\]