What is causing this error of black mark question marks?

Here is a pic

and here is the code

bsign= when b<0 "" otherwise "+"

correct=when a<0 and choice2.isSelected(1) and not(choice.isSelected(1)) and not(choice2.isSelected(2)) and not(choice.isSelected(2)) 1
        when not(a<0) and choice.isSelected(1) and not(choice.isSelected(2)) and not(choice2.isSelected(1)) and not(choice2.isSelected(2)) 1
        otherwise 0
co= when correct=1 "Correct!" otherwise "Not there yet keep working"
content: "

Which statement is true when comparing how a student would complete the
solution for the linear equation `${a}𝑥${bsign}${b}=${c}` to how the student would
complte the solution for the linear inequality `${a}𝑥${bsign}${b}<${c}`

Your answer: ${co}

Your x in the content looks like it’s italic. Maybe it’s a character that’s not recognized?

That is weird. I copied it from my other activity that did not have that and worked fine. I wonder what made it become italic.