Which of the following is the correct way to declare a string object in Java?

The declaration of a string object in Java is correctly represented by the option that indicates creating an instance of the String class using a constructor that initializes the string with specific content. In this case, declaring a string like this utilizes the new keyword combined with a constructor. Therefore, creating a string this way establishes an actual String object.

In Java, strings are objects and can be declared using either the string literal syntax or the new keyword with constructors. The option that reflects this usage correctly indicates that a new instance of a String object is created. This approach highlights that a string can be manipulated like any other object in Java, allowing for methods associated with the String class to be applied to it after initialization.

For understanding, the other options do not appropriately represent a correct or standard way to declare a string object in Java. For example, while a string literal like "Hello" is valid, the usage of the new keyword without an initialization value or with an underscore (which is a naming convention violation) does not showcase standard practices or proper object instantiation in this context.