Toggle show/hide to a specific element - reactjs

Question

I have this particular code that shows a list of questions and buttons for each of it. When I click the button, it will show the specific answer to the question. My problem is, I have a bunch of questions and when i click the button, it will show all of the answer instead of the specific answer to that question.
Here is the code
class App extends React.Component {
constructor(){
super()
this.state = {
answer: [],
isHidden: true
}
this.toggleHidden = this.toggleHidden.bind(this)
}
componentWillMount(){
fetch('http://www.reddit.com/r/DrunkOrAKid/hot.json?sort=hot')
.then(res => res.json())
.then( (data) => {
const answer = data.data.children.map(obj => obj.data);
this.setState({answer});
})
}
toggleHidden(){
this.setState({isHidden: !this.state.isHidden})
}
render(){
const answer = this.state.answer.slice(2)
return <div>
<h1>Drunk or Kid</h1>
{answer.map(answer =>
<div key={answer.id}>
<p className="title">{answer.title}</p>
<button onClick={this.toggleHidden}>Answer</button>
{!this.state.isHidden && <Show>{answer.selftext}</Show>}
</div>
)}
</div>
}
}
const Show = (props) => <p className="answer">{props.children}</p>
And here is the link to the codepen

Answer 1

Here is a Codepen based on my suggestion:
The basics of the child component would be:
class Question extends React.Component {
// Set initial state of isHidden to false
constructor() {
super();
this.state = {
isHidden: false
}
}
// Toggle the visibility
toggleHidden() {
this.setState({
isHidden: !this.state.isHidden
});
}
// Render the component
render() {
const { answer } = this.props;
return (
<div key={answer.id}>
<p className="title">{answer.title}</p>
<button onClick={ () => this.toggleHidden() }>Answer</button>
{this.state.isHidden && <Show>{answer.selftext}</Show>}
</div>
);
}
}
Then you would map over it within the parent component as:
answer.map(answer =>
<Question answer={answer} key={answer.id} />
)

Answer 2

Another option is to add a state that save opened answer id, then checking if specific answer in that state or not.
let's see in action
class SomeComponent extends React.Component {
constructor(props){
super(props)
this.state = {
opened: []
}
this.toggleShowHide = this.toggleShowHide.bind(this)
}
toggleShowHide(e){
const id = parseInt(e.currentTarget.dataset.id)
if (this.state.opened.indexOf(id) != -1){
// remove from array
this.setState({opened: this.state.opened.filter(o => o !== id)})
} else {
this.setState({opened: [...this.state.opened, id]})
}
}
render(){
return <ul>
{ this.state.answers.map(ans => (
<li key={ans.id} data-id={ans.id}>
question
<button onClick={this.toggleShowHide}>show answer</button>
<span
style={{ display: this.state.opened.indexOf(ans.id) !== -1 ? 'block' : 'none' }}>answer</span>
</li>
))}
</ul>
}
}
Here is video in action https://www.youtube.com/watch?v=GJsPEsckB4w