In the following sequence of reactions,
CH₃CH₂OH $$\buildrel {P + {I_2}} \over \longrightarrow $$ A $$\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{ether}^{Mg}} $$ B $$\buildrel {HCHO} \over \longrightarrow $$ C $$\buildrel {{H_2}O} \over \longrightarrow $$ D
the compound ‘D’ is

Phenyl magnesium bromide reacts with methanol to give

HBr reacts with CH₂ = CH – OCH₃ under anhydrous conditions at room temperature to give

The structure of the compound that gives a tribromo derivative on treatment with bromine water is