What will be the output of the following PHP code? <?php $a1 = array_fill(1, 4, "hello"); $b1 = array_fill(5, 1, "php"); $a2 = array_merge($a1, $a2); print_r($a2); echo ""; print_r($b1); ?>

• A. Array ( [1] =&gt; hello [4] =&gt; hello [5] =&gt; php )
• B. Array ( [1] =&gt; hello [2] =&gt; hello [3] =&gt; hello [4] =&gt; hello )
• C. Array ( [1] =&gt; hello [2] =&gt; hello [3] =&gt; hello [4] =&gt; hello [5] =&gt; php )
• D. Array ( [1] =&gt; hello [2] =&gt; hello [3] =&gt; hello [4] =&gt; hello )