Exam 1z0-819 topic 1 question 107 discussion

Tested, C

The correct answer is C. The code s.replace(s.indexOf("B"), s.indexOf("C"), "Q") would cause s to be "AQCD". The replace method of the StringBuilder class replaces the characters in a substring of this sequence with characters in the specified String. The substring begins at the specified start index and extends to the character at index end - 1 or to the end of the sequence if no such character exists. In this case, s.indexOf("B") returns 1, which is the start index of the substring to be replaced, and s.indexOf("C") returns 2, which is the end index of the substring to be replaced. So, the character at index 1 ("B") is replaced with "Q", resulting in "AQCD".