#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;

use Data::Dumper;

my $choices = [
    [
        'a',
        'W',
        'interupt',
    ],
    [
        'b',
        'R',
        'interrupt',
    ],
    [
        'c',
        'W',
        'innterupt',
    ],
    [
        'd',
        'W',
        'intterupt',
    ]
];


my $answer = 'd';
# As we know that the answer matches only one choice
# and we have exactly one matching answer.
my $chosen_answer = (grep { $_->[0] eq $answer } @$choices)[0];
say Dumper($chosen_answer);