Final answer:
The correct product of adding bromine water to but-1-ene is 1,2-dibromobutane, where each carbon atom of the former double bond in but-1-ene gets a bromine atom.
Step-by-step explanation:
The main organic product formed when bromine water is added to but-1-ene is not listed among the options A, B, C, or D. The correct product of this reaction is 1,2-dibromobutane. This is because the addition of bromine to an alkene like but-1-ene involves a reaction where the double bond is opened up, and a bromine atom is added to each of the two carbon atoms that were previously double-bonded (the first and second carbon atoms in this case).
In the case of reacting with but-1-ene, since there are four carbon atoms and the double bond is between the first and second carbon atoms, the bromine atoms will add to these two carbons, leading to the formation of 1,2-dibromobutane.