I have a question about "The verbs with the general meaning of suggestion and form of verbs"
a) She declined a seat beside Charles on the sofa. She insisted that Jane sit there. (subjunctive verb)
b) She declined a seat beside Charles on the sofa. She insisted that Jane sits there.(indicative verb)
c) She declined a seat beside Charles on the sofa. She insisted that Jane sat there.
sentence a and sentence b are grammatically correct in my opinion but I am not sure about sentence c. is sentence c grammatically and idiomatically correct?
I have seen a sentence in this structure (sentence c) in a website but I have not seen somewhere else.