By Homographs, Pronouns

#2 and #3 are correct. The others are not. In your first pair, you have constructed compound sentences; 'that' (the demonstrative pronoun, which here refers to the first independent clause) is the subject of the second independent clause; 'that' is singular and takes the 3rd person singular...

Hi DK, Welcome to englishforums. "Press on the wound. That will stop the bleeding". The 'that' is not a relative pronoun for a dependent clause. It is a different word (with a different pronounciation); it is the demonstrative pronoun for 'pressing on the wound'. I have not pursued all...