Prevent respondent from changing default answer

Hello there! 

I’m sure someone will be able to provide you with a way to use code to not allow this, but one workaround you could leverage would be to use validation:

You can locate this by selecting your question and in Response Requirements adding custom validation with the criteria above. While it would allow the respondent to change their answer during the survey, they cannot continue to the next page of the survey (or finish the survey) until Option 1 is the one that remains selected. 

@Deepak thanks for your great reply.

jQuery('#'+this.questionId).find('input').eq(1).prop('disabled',true);

As a follow-up to this, is it possible to also change the CSS styling of the non-default and default answers across multiple questions? For example, I tried something like this by inserting it into custom CSS under Look & Feel, but it applied the styling to the top and bottom response option, rather than to the default and non-default response option.

#question1 .ChoiceStructure li.Selection.alt label,
#question2 .ChoiceStructure li.Selection.alt label {
  opacity: 0.6; /* Reduce the opacity of the non-default option */
}

/* Style the default option to make it more prominent */

#question1 .ChoiceStructure li.Selection.reg label,
#question2 .ChoiceStructure li.Selection.reg label {
  font-weight: bold; /* Make the default option bold */
}

@Deepak Great, thank you again! I made a minor modification, which is to change MultipleAnswer to SingleAnswer, as this is a single answer multiple choice question. I also have a question: how would I use JS to change the CSS styling of the non-default option instead?