The reduction product of ethyl 3-oxobutanoate by NaBH₄ in methanol is

What is the major product of the following reaction?

The correct order of reactivity for the addition reaction of the following carbonyl compounds with ethylmagnesium iodide is

$$[P]\buildrel {B{r_2}} \over \longrightarrow {C_2}{H_4}B{r_2}\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{N{H_3}}^{NaN{H_2}}} [Q]$$

$$[Q]\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{H{g^{2 + }},\Delta }^{20\% /{H_2}S{O_4}}} [R]\buildrel {Zn - Hg/HCl} \over \longrightarrow [S]$$

The species P, Q, R and S respectively are