The major stereoisomer P obtained in the following reaction is (S)-2-butanol.
The reaction is an E2 elimination reaction, which proceeds through a concerted mechanism. The rate-determining step involves the formation of a three-membered transition state. In this transition state, the C-C bond between the β-carbon and the leaving group is breaking, while the C-H bond on the β-carbon is forming. The stereochemistry of the product is determined by the configuration of the C-C bond in the transition state. In this case, the C-C bond in the transition state is in the anti-periplanar conformation, which means that the C-H bond on the β-carbon is in an axial position and the leaving group is in an equatorial position. This conformation leads to the formation of the (S)-2-butanol product.
The other options are incorrect because they do not have the correct stereochemistry. Option A is (R)-2-butanol, which is the enantiomer of the desired product. Option B is 2-methylpropene, which is the product of an E1 elimination reaction. Option C is 2-butanol, which is the product of an S N2 reaction. Option D is 1-butanol, which is the product of an S N1 reaction.