In displacement reactions (reactions in which an element replaces another element in a compound) like these, reactive element displaces the less reactive element.
A. NaBr + I2
This reaction will not occur because Iodine is not able to displace bromine from the compound.
B. KBr + F2
This reaction will occur because flourine is more reactive and hence is able to displace bromine from the reaction.
C. LiF + Cl2
This reaction will not occur because chlorine is not able to displace flourine from the compound.
D. NaCl + I2
This reaction will not occur because Iodine is not able to displace Chlorine from the compound.
