Which sentence/sentences is/are correct gramatically?

[slatyb]

C is nearly correct, but “My Instagram FOLLOWING is decreasing”:is better, Your use of less is common among South Asian speakers, but sounds strange to others. In standard English, “fewer” is used with countable nouns, “less”:with uncountable nouns. Many speakers use “less” for both in conversation.

[MrEscanor]

C seems like the best answer.
My Instagram followers are getting lesser and lesser is grammatically correct one.

[lanadelrey25]

c) My instagram followers are decreasing

[SarahL98]

C if I'm not mistaken

[Iron_Man]

My Instagram followers are getting less.

[jjj101010]

None of the above

[Anonymous]

Definitely C.