Which of the following is the condensed structural formula for 2-pentene?
A. CH₃ - CH₂ - CH₂ - CH = CH - CH₃
B. CH₃ -CH₂ - CH = CH - CH₃
C. CH₂ - CH = CH -CH₂ - CH₂ - CH₃
D. CH₂ = CH - CH₂ - CH₂ - CH₃