title: How to know if a mat-option is selected or not from a click event?
body: <p>I have a multiple <code>mat-select</code> and would like to know if the <code>mat-option</code> that's been clicked has been selected or deselected. The <code>$event.target</code> object passed when the <code>(click)</code> is fired has no <code>selected</code> attribute I could use.</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;mat-form-field&gt;
      &lt;mat-select [formControl]="control" multiple&gt;
          &lt;mat-option 
            *ngFor="let option of options" 
            [value]="option"
            (click)="foo($event)"
          &gt;
          {{ option }}
          &lt;/mat-option&gt;
      &lt;/mat-select&gt;
  &lt;/mat-form-field&gt;
  </code></pre>
  
  <pre><code>public foo(event) {
      const hasBeenChecked = ???? // How do I know if my clicked option has been checked or unchecked?
  }
  </code></pre>
  
  <p>Thanks in advance</p>