Enthuware

Why is the first option less correct in than the others?

First option is wrong because a request may be sent to the server through some other client. So, validation must be done at the server.

If this is the reason why 1 is incorrect, than the wording should be "validate input IN client side" or "validate input AT client side". "From" client side means input coming from outside the application, which should be validated. Option 1 actually means that validation should be done at the server, in the way its written now.

You are right. Fixed.
thank you for your feedback!