Final answer:
In radical monobromination, the number of different products depends on the number of hydrogen atoms bonded to the carbon atom being replaced. In this case, if there are 2 hydrogen atoms, two different products will result.
Step-by-step explanation:
In radical monobromination, a hydrogen atom is replaced by a bromine atom through a radical mechanism. Since the question specifies that the reaction occurs only at the 3rd carbon atom, we need to identify how many hydrogen atoms are bonded to this carbon. If there is only one hydrogen atom, then only one product will result. However, if there are two hydrogen atoms, there will be two possible products. Therefore, the correct answer is (b) 2.