Which of the following compounds responds to both iodoform test and Fehling's test?

Reactant $(A)$ is:

Which of the following compounds does not give Tollen's test?

The reaction shown in the image proceeds via which mechanism?

An ester $(A)$ with molecular formula $C_9H_{10}O_2$ was treated with excess of $CH_3MgBr$ and the complex so formed was treated with $H_2SO_4$ to give an olefin $(B)$. Ozonolysis of $(B)$ gave a ketone with molecular formula $C_8H_8O$ which shows positive iodoform test. The structure of $(A)$ is

In the given reaction $C_6H_5CHO + X \xrightarrow{(i) Zn, (ii) HOH/NH_4Cl} C_6H_5-CH(OH)-CH_2-COOC_2H_5$,$[X]$ will be: