The correct answer is:
Its boundaries were expansive, including countries in arctic and tropical climates.
<em>"God of our fathers, known of old</em>
<em>Lord of our far-flung battle-line</em>
<em>Beneath whose awful Hand we hold
</em>
<em>Dominion over palm and pine"</em>
In this sentence "Dominion over palm and pine" they make reference to the British empire expansion, where they included arctic countries and troplical climates.