To solve this question, the user needs to be familiar with client-side web development techniques.

The correct answer is option A, which is cookies.

Explanation:

Cookies are small text files that are stored on the user's computer by a website. They are used to store user preferences, login information, and other relevant data. Since cookies are stored on the user's computer, they can be easily disabled by the end-user. Users can disable cookies in their browser settings or use a browser extension to block them.

Option B, query strings, cannot be disabled by the end-user. Query strings are a part of the URL, and they are used to pass data between a web server and a client. They are not stored on the user's computer, so they cannot be disabled by the end-user.

Option C, view state, is a technique used in ASP.NET web development to store state information on the client-side. View state is not a client-side technique that can be disabled by the end-user. It is generated by the server and sent to the client as a hidden field in an HTML form.

Option D, both A and B, is incorrect because query strings cannot be disabled by the end-user.

Option E, all of the above, is incorrect because view state cannot be disabled by the end-user.

Therefore, the correct answer is:

The Answer is: A. Cookies