The correct answer is C.
All these presidents were sworn into office after the sitting president died.
Calvin Coolidge served as the 30th president of the United States from 1923 to 1929. He was the vice president and he succeeded to the presidency upon the sudden death of Warren G. Harding in 1923.
Harry S. Truman was the 33rd president of the United States from 1945 to 1953. He was serving as vice president and was made president upon the death of Franklin D. Roosevelt.
Theodore Roosevelt served as the 26th president of the United States. He was the vice president and he became president after the assassination of the former president, William McKinley.