`CH-=CHunderset(C Cl_(4))overset(Br_(2))to[A]overset(Zn)to[B]`

Explanation

To solve the given question step by step, we will follow the reactions involving acetylene, bromine, and zinc.

### Step 1: Identify the Reactant
The reactant given is acetylene, which has the structure:
\[ \text{CH} \equiv \text{CH} \]

### Step 2: Reaction with Bromine in CCl4
Acetylene reacts with bromine (\( \text{Br}_2 \)) in the presence of carbon tetrachloride (\( \text{CCl}_4 \)). This reaction will lead to the addition of bromine across the triple bond of acetylene, resulting in the formation of a dibromide.
...