Working the Virginia City Comstock Lode was extraordinarily dangerous. In addition to the risk of cave-ins and underground fires, miners had to worry about .

a.
toxic fires.
c.
overcrowded conditions.
b.
gas explosions.
d.
underground flooding.

your list doesn't mention any of them at all.

and what does "these" mean anyway ?

the california missions began in the late 18th century as an effort to convert native americans to catholicism and expand european territory. there were 21 missions in all, lasting from 1769 until about 1833.   the missions were built by the spanish starting in 1769 in order to “colonize” the territory of alta california. so the missions were important because they were the means of settling california. it also wanted to keep other european countries out of alta california. building settlements along the coast would them meet these goals. missionaries wanted to convert the indians to the roman catholic faith. california indians did much of the work to build missions.

answer; (d) i believe that the correct answer is americans finally ran out of ammunition;

the chinese communist party (ccp);

explanation: