Institution: SONALI BANK LTD Exam: Sonali Bank Ltd - Assistant Programmer - 26.08.2016 ||
Topic: ICT (তথ্য ও যোগাযোগ প্রযুক্তি), Subject: Computer and ICT (তথ্য ও যোগাযোগ প্রযুক্তি)

Best Answer Explained in Below-:

In programming, an identifier is a name used to identify a variable, function, class, or other entity. Each programming language has specific rules regarding what constitutes a valid identifier. Common rules include that identifiers must start with a letter (a-z, A-Z) or an underscore (_), followed by letters, digits (0-9), or underscores. They cannot contain special characters or spaces.

Examining the options provided:

A) **-mysun**: This is invalid because it starts with a hyphen, which is not allowed.

B) **mysun**: This is a valid identifier. It starts with a letter and has no illegal characters.

C) **my-sun**: This is the key option to focus on. It contains a hyphen. In many programming languages, such as Python, Java, or C, the hyphen is interpreted as a subtraction operator and thus cannot be part of an identifier.

D) **my.sun**: This may depend on the programming language, but in many contexts (e.g., JavaScript, Python), the dot is allowed for accessing properties but not as part of the identifier itself. However, it is usually at least usable in context.

Thus, the correct answer is C) **my-sun**, as it violates the fundamental rule prohibiting special characters other than underscores in identifiers.