use strict;
use warnings;
use Data::Dump;

my %answers;
my $question;

while (my $line = <DATA>)
{
    if    ($line =~ / ^ (\d+) \. /x)
    {
        $question = $1;
    }
    elsif ($line =~ / ^ \* (\w+) \. \s* (.*?) \s* $ /x)
    {
        warn "Overwriting answer for question $question"
            if exists $answers{$question};

        $answers{$question} = [$1, $2];
    }
}

dd \%answers;

__DATA__
1. question?
*a. answer begin end
b. answer 
c. answer 
2. question?
a. answer 
*b. answer 
c. answer 
3. question?
a. answer 
b. answer 
*c. answer