ayushiiitm wrote:114. Ancient Romans found it therapeutic to bathe in cold milk, in strawberries that had been crushed, or in bathtubs filled with black caviar.
(A) to bathe in cold milk, in strawberries that had been crushed, or in bathtubs filled with black caviar
(B) that they bathe in cold milk, in strawberries that had been crushed, or in caviar that was black
(C) to bathe in cold milk, crushed strawberries, or black caviar
(D) that they bathe in cold milk, crushed strawberries, or black caviar
(E) to bathe in milk , strawberries, or caviar

Though I can make out that c is the best choice due to preciseness, I am having a doubt in concept

When do we use a infinitive form of verb and when do we use 'that'?

I know a bit: by definition 'that' is a relative pronoun so used to join subjunctive clauses. Is that the only use, or are there more uses of 'that' in situations such as given in above example

I am getting very curious.....please tell me.