Which of the following reactions gives $H_2C=C=C=CH_2$?

$CH \equiv CH$ $\xrightarrow{HCl \text{ (Excess)}} A$ $\xrightarrow{\text{Hydrolysis}, \Delta} B$ $\xrightarrow{\text{Reduction}, Na-Hg / H_2O} C$
Compound $C$ is

The incorrect statement regarding ethyne is

Identify the alkyne in the following sequence of reactions:
Alkyne $\xrightarrow{\text{H}_2, \text{Lindlar's catalyst}} A$ $\xrightarrow{\text{Ozonolysis}} B \text{ (only)}$
Given that $B$ is obtained from $\text{CH}_2=\text{CH}_2$ via the Wacker process.

The reagent needed for converting $Ph-C \equiv C-Ph$ to trans-stilbene is:

The simplest alkyne is represented by