Bunuel
Many of them dug during the Greenwood copper boom a century ago, the hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines.(A) Many of them dug during the Greenwood copper boom a century ago, the hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines.
(B) Dug during the Greenwood copper boom a century ago, the hills to the east of Death Valley, Arizona, are dotted with many hundreds of copper mines.
(C) Hundreds of copper mines, most of them dug during the Greenwood copper boom a century ago, are dotting the hills to the east of Death Valley, Arizona.
(D) The hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines, most of them dug during the Greenwood copper boom a century ago.
(E) The hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines, most of which aredug during the Greenwood copper boom a century ago.
(A) Many of them dug during the Greenwood copper boom a century ago should refer to the “mines”, not to “the hills”.
(B) Dug during the Greenwood copper boom a century ago, should refer to the “mines”, not to “the hills”.
(C) “are dotting# is the incorrect tense. The tense should be present simple.
(D) The hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines, most of them dug during the Greenwood copper boom a century ago.
Correct. The modifier is next to “mines” , and the verb is in present simple.
(E) The hills to the east of Death Valley, Arizona, are dotted with hundreds of copper mines, most of which are dug during the Greenwood copper boom a century ago. “are dug” should be “were dug” because it happened in the past.
However, I believe that the original sentence states “many of them”. That expression is changed for “most of them” in the other answers and thus, it changes the original meaning.