Actually this the fundamental of React that you should not name your component starting with smaller case letter.
This is how the react render method figure out that this is a user-defined component or predefined tag's.
consider an example.
suppose you have made a component called img for getting Image on the page and you name that component in a smaller case then render method will get not take your component but it will render normal HTML img tag
so it you want to correct it you have name it as Img.
In your case, you can do like this
const Quiz = () =>{
}
or
class Quiz extends React.Component {
}