What is the significance of the left lung having two lobes?

The left lung having two lobes is significant primarily because it accommodates the heart's position. The heart is located slightly to the left side of the thoracic cavity, which is why the left lung is smaller and has only two lobes compared to the right lung, which has three lobes. This anatomical adaptation ensures that there is enough space for the heart to occupy its proper location without compromising the overall functionality of the respiratory system.

While aspects such as lung capacity, air exchange efficiency, or weight might seem relevant, the design of the lung structure is fundamentally influenced by the need to allow room for the heart, making option B the most accurate answer in this context.