Why "it" is used for two words connected with or?

could you please tell me why we use "it" and "that" as singular pronouns in this sentence? Do we always do the same in Eglish or we can you use plural pronouns instead too? :

Blockquote Skin too light or too dark? Creams can handle that. Gummy smile or biggish nose? Surgery can remake it.


These are not parallel constructions, and that may be confusing you.

Skin too light or too dark? Creams can handle that.

Here, that refers to the (singular) situation.

Gummy smile or biggish nose? Surgery can remake it.

Here, it refers to the (singular) situation.