The Tiobe index is a popular and much quoted and updated monthly list of programming languages sorted by popularity. And in May 2020, it lists C as the top language.
Now call me cynical; I do like C (kind of obvious- duh!) but I do have my misgivings about this index. For one, other programming language popularity measures usually disagree with it but are more consistent. Here are some. Most other articles seem to quote from these particularly the StackOverflow developer survey.
RedMonk – C is ninth.
Reddit’s programming language sub-reddits. C is ninth on here.
PyPl – how often language tutorials are searched on Google. C does not appear at all!
StackOverflow developer survey 2019. C is eleventh in their listed technologies.
Github Octoverse. You have to scroll down to Top languages. C is ninth.
Codingame 2020 Survey. You have to scroll down. C is 6th in most loved and most known (5th in most dreaded!)
Now each of these measures different things so they are never going to be that consistent but coming ninth in three different surveys is pretty telling, with one eleventh and one sixth. So when you see things like Tiobe, please take this with a pinch of salt.