Q.27 Geometrical isomer (text Q3.6)

Which of (a) to (f) is the concise structural formula of 2-butene?(a) CH3CBr=CHBr, (b) CH3CH2CH=CH2, (c) CH3CBr=CHCH2Br,(d) CH3CH=CHCH3, (e)CH3CH=C(CH3)2.