The addition in unsymmetrical alkenes follows the Markovnikov rule, according to which the negative part of the addendum goes to the carbon having lesser number of hydrogens.

The step-1 involves ozonolysis to form hexan-1,6-dione.
The step-2 involves aldol condensation in the presence of a base to form α, β-unsaturated aldehydes.

4-Methyl-penta-1,3-diene on ozonolysis yields methanal, glyoxal and acetone.

The given reaction is an example of dehydrohalogenation of alkyl halides in the presence of alc. KOH.

The acidic nature of acetylene is due to the greater sigma electron density of C-H bond of acetylene towards carbon, which is sp hybridised and has 50% of s-character.
Hence, the electron pair of C-H bond gets displaced towards the carbon atom; and as a result, abstraction of H⁺ ion becomes easier.

Since the alkyne is reduced to an alkene, and cis product is formed, the reducing agent is H₂/Pd, BaSO₄ (Lindlar's reagent).

Reagent I is a Lewis acid that catalyses the electrophilic substitution (acylation) of the benzene ring.
Reagent II is Zn-Hg,HCl that brings Clemmensen reduction of carbonyl compounds to form hydrocarbons.

(A), (C) and (D) are aromatic as there is complete conjugation and they obey Huckel's rule of (4n + 2) π-electrons.

Both methyl group (–CH₃) and methoxy group (-OCH₃) are ortho and para directing, and activating groups.
Since the effect of methoxy group is stronger, the major product will have bromine substituted at the para position with respect to the methoxy group.