Ionic 4 change background dynamically of dynamical variables - ionic4

Question

I'm building a quiz app just for fun. But I'm not getting what I want.
Basically, I have a question and answers (a-e options).
When I click a answer, I want to change the background (card) dynamically just for the selected. If was wrong, change this color to red and the correct one for green.
Simplified html
<ion-row>
<ion-col size="12" style="padding: 0;">
<ion-card class="card__wrapper card__{{answer.option}}" *ngFor="let answer of question.answers" tappable (click)="chooseAnswer(answer)" [style.backgroundColor]="answer.is_correct ? correct : 'color'+answer.option">
<ion-card-content class="card__content">
<ion-row>
<ion-col size="2" style="padding: 0;">
<div class="option__wrapper">
<p class="answer__option">{{answer.option}}</p>
</div>
</ion-col>
<ion-col size="10" style="padding: 0; margin: auto;">
<p style="text-align: left; margin: 0;"[innerHTML]="answer.description"></p>
</ion-col>
</ion-row>
</ion-card-content>
</ion-card>
</ion-col>
</ion-row>
Simplified .ts
public correct: string = '#fff';
public wrong: string = '#fff';
public slidePage = '0';
public colorA = '#fff';
public colorB = '#fff';
public colorC = '#fff';
public colorD = '#fff';
public colorE = '#fff';
chooseAnswer(answer) {
if (answer.is_correct) {
this.correct = '#00e676';
} else {
switch (answer.option) {
case "A":
this.colorA = 'red';
break;
case "B":
this.colorB = 'red';
break;
case "C":
this.colorC = 'red';
break;
case "D":
this.colorD = 'red';
break;
case "E":
this.colorE = 'red';
break;
}
this.correct = '#00e676';
}
}
So there are two cases:
Select correct answer
Set background of the selected answer to green
Select wrong answer
Set background of the selected answer to red and set background of the correct answer to green.