Want to get value out of angular2 ngfor button loop from async call

Question

I have an async for loop from an observalble which is an object of an array. I want to know how can I get the value out of this array when the button is clicked?

The object of array is like this: { topics: [ "first choice", "second choice", "third choice" ] }

<button *ngFor = "let choice of (choices | async)?.Topics">
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Answer 1

<button *ngFor = "let choice of (choices | async)?.Topics" 
    (click)="clickHandler(choice)">