This reaction involves the addition of HBr to a conjugated diene, which proceeds via 1,2-addition and 1,4-addition mechanisms. The reaction is under kinetic control at low temperature, favoring the 1,2-adduct. The major products are the ones formed from the more stable carbocation intermediate. The bromonium ion can form on either carbon of the double bond, but addition to the terminal carbon generates a more stable secondary carbocation. This leads to the pair of 1,2- and 1,4-addition products where bromine is on the secondary carbon.

Final Answer: The first pair of options is the major product.