Thank you very much, I'm grateful for your answer.
I thought of the option of or,
but some how I have in mind that "sel" appears as avariable of 0 and 1 simultaneosly, in order to give the value 1.
I know there is a logicel mistake in my mind, I cannot find it.
No signal can be 0 and 1 simultaneously (this isn't quantum computing!).
Your 'sel' and 'notsel' are mutually exclusive -- one of them is a 0 and the other is a 1. When you And them with their respective inputs, the one that is 0 forces the output of that channel to be 0 regardless of the value of the input. If one input to an Or or an Xor is 0, then the output is equal to the other input. Hence they become equivalent in this instance.