Which of the following is $NOT$ prepared by the action of Grignard's reagent on methanal?

$3, 3-$Dimethyl$-2-$butanol cannot be prepared by:
Choose the correct answer from the options given below :

Explain the method of obtaining alcohols from carboxylic acids and esters.

Show how will you synthesize:
$(i)$ $1-$phenylethanol from a suitable alkene.
$(ii)$ cyclohexylmethanol using an alkyl halide by an $S_{N}2$ reaction.
$(iii)$ pentan$-1-$ol using a suitable alkyl halide?

In the following reaction,$'A'$ is:
$C_2H_5MgBr + CH_2(O)CH_2 \xrightarrow{H_2O} A$

Preparation of alcohols from alkenes involves the electrophilic attack on alkene carbon. Explain its mechanism.