While other writers from his time have faded into obscurity, Thoreau has endured for all these reasons but_____________________.
选项：

A:So much of what he wrote about is still relevant today.;
B:His major work, Walden, is a transcendentalist work.;
C:His writings on government were revolutionary, with some calling him an early anarchist. ;
D:Thoreau's studies of nature were equally radical in their own way, earning him the moniker of