You should welcome wrong answers, because students learn those which are correct by comparing them with those which are incorrect.
Thus, what you should welcome is not a correct answer, but wrong answers.
If students do not make wrong answers, make a "good" wrong answer by yourself. And ask students :
"How about this ? For me, it seems to be correct."
Students become confused, and start to think. Or, students try to find reasons why it is not correct. There is no exercise better than this.
Don't treat a wrong answer as if it were a bad thing.
If you remove/exclude wrong answers rather than welcome them, then students become afraid of making mistakes. This is the worst !
Suppose that your student write a wrong answer on the blackboard. What do you do? Will you errase it and look for a student who can write a correct answer ?
Don't do this !
Remember : One learns by making mistakes, and progresses.
Thus, what you should do is to encourage students to make many mistakes and to make many wrong answers.