The intermediate X, in the reaction

Explanation: The reaction is the Reimer-Tiemann reaction used for converting phenol into salicylaldehyde.

Chloroform reacts with aqueous $$NaOH$$ to generate dichlorocarbene:

$$:CCl_2$$

The basic medium converts phenol into phenoxide ion, making the ortho position highly nucleophilic.

The ortho position attacks the electrophilic dichlorocarbene, forming an intermediate containing a dichloromethyl group:

$$-CHCl_2$$

Thus, intermediate $$[X]$$ contains an ortho $$-CHCl_2$$ substituent along with the phenoxide group.

On treatment with aqueous $$NaOH$$ followed by acidic workup, the $$-CHCl_2$$ group undergoes hydrolysis to form the aldehyde group:

$$-CHO$$

Finally, protonation restores the phenolic $$-OH$$ group, giving salicylaldehyde.

Therefore, intermediate $$[X]$$ is the ortho-dichloromethyl substituted phenoxide intermediate. Thus, the right option is C.