Answer: A) Our love can endure our physical absence from each other.
The above lines state that Donne and his love are two souls, yet united as only one. Because they are a single entity, when Donne goes away (which he has to do), as they separate, their love does not experience a "breach," but instead, an "expansion." As if their love was stretched throughout the distance in the form of very thin gold.
The best option, therefore, is A, as it states that their love can endure physical absence from each other. Their love does not become any thinner, nor does he states that their souls are like gold. Finally, he clarifies that what they will endure is NOT a breach, but an expansion.
