Answer:
str[0].toUpperCase(); is the correct answer to the following question.
Step-by-step explanation:
In the following code is the code which is in the Java Programming Language.
Here, the variable "str" is the string data type array variable which contains characters or words and the index 0 "[0]" indicating the first element of the string array then, "toUpperCase()" is the built-in function that is used to convert lowercase string characters or words to the upper case.
So, the following code converts the first element of the string into the upper case.