It was rejected as something along the lines of "This edit is too short to improve it". I don't have the exact wording, didn't grab a screenshot. Confused, I tried again, this time adding an edit comment like "added c tag". Same result.
Now, I get that it's a short edit, but it had no language tag, while the OP was clearly asking about c. From what I've seen here on meta, tag edits shouldn't normally be rejected as "too minor".
To be clear, this was not a suggested edit, since I have the editing privilege.
To add insult, a minute later another user suggested the same edit(tag c only) and it was approved.