The Figure Below Documents the Loss of Old-Growth Forests in the United

The figure below documents the loss of old-growth forests in the United States over a 300-year period.
What best explains why the forests of the Pacific Northwest were relatively unaffected during that time period?

A) Legislation to protect endangered species like the spotted owl limited timber harvesting in the region.
B) The old-growth Douglass fir found in the region is unsuitable for most applications and the trees were simply ignored.
C) The U.S. population had not expanded significantly before 1920 and the timber of the eastern United States easily meet the needs of a smaller population.
D) Three hundred years is sufficient time to reestablish an old-growth forest, harvesting in the Pacific Northwest has simply been done sustainably.