Final answer:
The false statement about the volcanic mountain of Kohala is that it can still be classified as an active volcano; it is actually dormant. The correct option is B.
Step-by-step explanation:
The correct answer to the question about Kohala, a volcanic mountain on Hawai'i Island, is option B: Kohala can still be classified as an active volcano.
This statement is false because Kohala is actually considered to be a dormant, not an active, volcano. It is also the oldest of the five volcanoes that make up the island of Hawai'i.
It should be noted that Kohala indeed used to be much larger than it is today, confirming that option A is true. Furthermore, the statement in option C is also true as Kohala did lose some of its windward flanks due to an ancient catastrophic landslide.
As for option D, Kohala is indeed the subaerial volcano on Hawai'i Island that is geographically closest to Haleakalā on Maui. The correct option is B.