Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein.
When was Einsteinium first discovered?

D0g is a fictional character in the Half-Life series of video games, first introduced in Half-Life 2 in 2004.
What fictional work does D0g exist in?

The 10th Cavalry returned from the Philippines in late 1902 and settled down in different posts in the south western United States. Patrols and garrison life was the routine for the regiment. Under war plans, the 10th was designated for service in the Pacific and support in the Philippines from 1915 through 1942 but never rotated there. The 9th Cavalry Regiment became "Park Rangers" in 1905 for Yosemite National Park and other state and federal lands. The Troopers' Campaign Hat, sporting the "Montana Pinch" used to help shed the tropical downpours. That "Montana Pinch" gave the hat the distinctive look we recognize today as the "Smokey Bear Hat".

Which regiment did not create the Montana pinch hat, 9th or 10th?