What marks indicate that a comment appears after it in Java?

In Java, comments can be written in different ways, and the choice that indicates that a comment appears after it is the use of "//". This syntax allows developers to add single-line comments directly in their code. Anything following "//" on that same line is treated as a comment and is ignored by the compiler, making it useful for providing explanations or notes about the code without affecting its execution.

The other options represent different forms of comments or syntax in Java or other programming contexts. For instance, "/* and /" denotes multi-line comments, which begin with "/" and end with "/", allowing for comments that span across multiple lines. Choice C, which also includes "/* and", denotes documentation comments used for generating Javadoc, but these also do not imply that a comment follows them on the same line. Finally, the "#" symbol is used for comments in languages like Python but is not a part of Java's syntax.

Thus, the choice of "//" succinctly conveys that everything following this symbol on the same line is a comment, making it the correct answer for indicating that a comment follows in Java.