How do you alkylate an alcohol?
Oxidize the alcohol to the carbonyl, and then treat this with a carbanion..........
Or, deprotonate the alcohol, and then use this alkoxide to act on an alkyl halide to form an alkyl halide.
And thus (with a primary alcohol):
We get a secondary alkoxide..........
Alternatively, we could deprotonate the alcohol, and then treat this alkoxide with an alkyl halide to give an ether.
This question was unanswered for so long because of this ambiguity.