Consider the following method substringFound, which is intended to return true if a substring, key, is located at a specific index of the string phrase. Otherwise, it should return false.
public boolean substringFound(String phrase, String key, int index)
{
String part = phrase.substring(index, index + key.length());
return part.equals(key);
}
Which of the following is the best precondition for index so that the method will return the appropriate result in all cases and a runtime error can be avoided?
A. 0 <= index < phrase.length()
B. 0 <= index < key.length()
C. 0 <= index < phrase.length() + key.length()
D. 0 <= index < phrase.length() - key.length()
E. 0 <= index < phrase.length() - index
