The electrophile involved in the above reaction is

The reaction referred to is the Reimer-Tiemann formylation of phenol (or phenoxide ion) carried out with chloroform $$CHCl_3$$ and aqueous alkali $$KOH/NaOH$$.

Step-1 Generation of the reactive species from chloroform.
Under strong basic conditions, chloroform is first deprotonated:

$$CHCl_3 + OH^- \;\longrightarrow\; CCl_3^- + H_2O$$

Step-2 α-Elimination of chloride ion from the trichloromethanide ion:

$$CCl_3^- \;\longrightarrow\; :CCl_2 + Cl^-$$

The species $$:CCl_2$$ produced above has only six valence electrons on carbon; it is a neutral yet highly electron-deficient species. Such a species is called a carbene. Because the carbon atom lacks an octet, it readily seeks electrons and therefore behaves as an electrophile.

Step-3 Electrophilic attack on the activated aromatic ring.
The phenoxide ion is strongly activated toward electrophilic substitution. The electrophile that actually enters the ortho/para position of the ring is the dichlorocarbene $$:CCl_2$$ generated in Step-2.

Hence, the electrophile operating in the reaction is dichlorocarbene.

Option B which is: dichlorocarbene $$(:CCl_2)$$