Which of the options correctly combines the following two given sentences without changing the meaning? The patient had to stay in hospital. She had to get well.

• A.  The patient had to stay in hospital because she had to get well.  
• B.  The patient had to stay in hospital but she had to get well.
• C.  The patient had to stay in hospital while she had to get well.
• D.  The patient had to stay in hospital although she had to get well.