The correct increasing order of the reactivity of halides for `S_(N^(1))` reaction is:
A. `CH_(3)CH_(2)-Xlt(CH_(3))_(2)CH-XltH_(2)C=CHCH_(2)-XltPhCH_(2)-X`
B. `(CH_(3))_(2)CH-XltCH_(3)CH_(2)-X ltH_(2)C=CHCH_(2) ltPhCH_(2)-X`
C. `PhCH_(2)-Xlt(CH_(3))_(2)CH-XltCH_(3)CH_(2)-XltH_(2)C=CH-CH_(2)X`
D. `H_(2)C=CHCH_(2)-XltPhCH_(2)-Xlt(CH_(3))_(2)CH-XltCH_(3)CH_(2)-X`
