The data type is the type specifier that tells what kind of value the constant holds. It appears before the constant’s name, such as in a declaration like const int MAX = 100, where int is the data type. The name is the identifier you use to reference the constant, and the value is the literal assigned to initialize it. The access specifier, if present, controls visibility but is not the data type. So the data type is the part that specifies the kind of data stored by the constant.

Strings in Java are reference types, not primitive values. They are implemented as objects of the String class, which lives in the java.lang package. Because it’s a class, String is a non-primitive type. Strings are immutable: once a String object is created, its character sequence cannot be changed, and operations like concatenation create new String objects. That combination—being a class in java.lang and a non-primitive type—is why this statement is correct. Other options miss or misframe the reality: primitive types are not objects and don’t have methods; string literals aren’t about being created by default in any special sense; and while Strings are immutable, that property comes from the class design, not from being primitive.

Unary operators are the ones that act on a single value. They take one operand and produce a result. Examples include the unary minus that changes the sign of a number (-x), the logical NOT that inverts a boolean value (!x), and even unary plus or bitwise NOT (~x). The key idea is how many inputs the operator needs: one input value. This sits in contrast to binary operators, which require two operands (like a + b), and to ternary expressions, which involve three operands. The other choices describe what the operator does in terms of producing values or having zero operands, rather than describing how many inputs the operator requires.

Explicit narrowing cast means you force a value into a type with a smaller range or precision using a cast operator. In the first line, (int) 3.99 explicitly converts the floating-point literal to an int, which trims the fractional part and can lose information. That exact use of (int) is what makes it a narrowing cast. The other lines rely on implicit conversions during assignment. Moving from int to double, long, or float expands the representable range (a widening conversion) and doesn’t use an explicit cast, so they don’t demonstrate a narrowing cast.