After reading through some of the comments, here is my opinion.

C would be a good language IF you know your students plan to get into IT, specifically a sector where the low level knowledge is useful. Beyond that, I assume your students probably use windows and I personally always find it a pain to work with C on windows outside of full IDEs like jetbrains and Visual Studio. It’s also a lot more work till you get some results that you are happy about. Unless you start with an Arduino, which I find pretty nice to get students interested in embedded stuff.

I don’t like JavaScript because I find it a mess although it is very useful for anything web related.

Given you said in another comment that this is meant to be a general purpose skill for your students I would strongly recommend python. While I dislike the dynamic type system, it is a very powerful language to get stuff done. You can quickly get results that feel rewarding instead of running into hard to fix issues that turn your students off of programming in general. Also it’s very useful outside of IT as a scripting language for analyzing data in basically any field or for generating nice plots for some document