What by-product is formed in the process of making phenol from cumene?

Consider the following sequence of reactions:
$C_6H_6 + CH_3CH=CH_2$ $\xrightarrow[heat]{H_3PO_4} A$ $\xrightarrow[2. H_3O^{+}, heat]{1. O_2, heat} B + C$
The products $(B)$ and $(C)$ are:

In the given reaction,identify $A$:
$C_6H_5-CH(CH_3)_2 + O_2$ $\rightarrow A$ $\xrightarrow{H_2O/H^+} C_6H_5OH + CH_3COCH_3$

Benzene diazonium chloride on boiling with dilute sulphuric acid gives:

Cumene on air oxidation in the presence of cobalt naphthenate forms:

Write the chemical reaction for the preparation of phenol from chlorobenzene.