At first, the pi-electrons from the double bond will pick up the proton from the HOH. This will leave one of the double bond carbons with a positive charge. The rule of Markovnikov states that the carbon with more hydrogens will take the hydrogen from the reactant. This makes that the second carbon will carry the positive charge. Because the carbon is bonded two other carbons, we call this a secondary carbocation. These are more stable than primary and less stable than tertiairy carbocations. The reason for this difference in stability is called ‘hyperconjugation’. The positive charge is stabilized by the sp3-orbitals of the carbon-hydrogen bonds. The first product is the right answer.
