The correct answer is: Option C Assertion is correct but Reason is incorrect. Explanation: In Williamson's synthesis, ethers are generally prepared by the nucleophilic substitution reaction of an alkoxide ion with a primary alkyl halide. The reaction mechanism typically follows the SN2 (bimolecular nucleophilic substitution) pathway. The assertion that n-propyl tert-butyl ether can be readily prepared in the laboratory by Williamson's synthesis is true. However, the reaction cannot proceed via SN1 mechanism when primary alkoxide ion attacks a tert-butyl halide. In fact, tert-alkyl halides are not suitable substrates for the Williamson synthesis because the SN2 mechanism does not work well with sterically hindered electrophiles like tert-alkyl halides. Therefore, while the assertion is correct, the reason provided is incorrect.