Which reagent will you use for the following reaction ?
`CH_(3)CH_(2)CH_(2)CH_(3)toCH_(3)CH_(2)CH_(2)CH_(2)Cl+CH_(3)CH_(2)CHClCH_(3)`
A. `Cl_(2)//UV` light
B. `NaCl+H_(2)SO_(4)`
C. `Cl_(2)` has in the dark
D. `Cl_(2)` gas in the presence of iron in dark.