Answer 1

https://www.sololearn.com/learn/1139/?ref=app

Answer 2

Be sure to use the Q/A's search-feature to avoid having your thread marked as a duplicate. Hope this helps.

--> Query: https://www.sololearn.com/Discuss?ordering=MostRecent&query=c+course

https://www.sololearn.com/Discuss/152181/c-course
https://www.sololearn.com/Discuss/327674/we-want-a-c-course-sololearn
https://www.sololearn.com/Discuss/383952/why-solo-offer-c-language-course
https://www.sololearn.com/Discuss/704850/why-no-c-course
https://www.sololearn.com/Discuss/809383/can-we-add-a-c-course
https://www.sololearn.com/Discuss/842260/why-don-t-we-c-language-course-in-sololearn-and-also-some-topics-like-awt-swings-in-java
https://www.sololearn.com/Discuss/848210/c-programming
https://www.sololearn.com/Discuss/909464/how-many-of-you-guys-want-c-tutorial-course-on-sololearn
https://www.sololearn.com/Discuss/993477/why-was-c-not-added-as-a-regular-tutorial
https://www.sololearn.com/Discuss/1027796/c-course
https://www.sololearn.com/Discuss/1042032/do-you-guys-think-the-c-course-ever-come-out
https://www.sololearn.com/Discuss/1056743/c-as-a-course-in-sololearn
https://www.sololearn.com/Discuss/1057259/why-isn-t-there-a-c-course-on-sololearn
https://www.sololearn.com/Discuss/1085989/a-course-on-c
https://www.sololearn.com/Discuss/1098283/how-comes-sololearn-doesn-t-have-a-c-tutorial-course
https://www.sololearn.com/Discuss/1131726/why-there-isn-t-any-c-course-available-on-sololearn

Answer 3

SoloLearn has the C course now:
https://www.sololearn.com/post/34110/?ref=app
Moreover, C language is available as a challenge weapon and you can submit quizzes😊🎉