To answer this question, the user needs to have an understanding of the Java switch statement syntax and the types of expressions and case labels that are allowed within it.

A switch statement allows a program to evaluate an expression and then execute one of several possible blocks of code, depending on the value of the expression. The expression and case labels must be of a compatible type. Compatible types are those that can be implicitly converted to each other without loss of information.

Now, let's go through each option and explain why it is right or wrong:

A. switch expression of type int and case label value of type char: This option is legal. The char type can be implicitly promoted to int, which means that a char can be used as a case label with an int expression.

B. switch expression of type float and case label value of type int: This option is illegal. The int type can't be implicitly converted to float, which means that an int cannot be used as a case label with a float expression.

C. switch expression of type byte and case label value of type float: This option is illegal. The float type can't be implicitly converted to byte, which means that a float cannot be used as a case label with a byte expression.

D. switch expression of type char and case label value of type long: This option is illegal. The long type can't be implicitly converted to char, which means that a long cannot be used as a case label with a char expression.

Therefore, the correct answer is:

The Answer is: A. switch expression of type int and case label value of type char