The ancient Inca city of Macchu Picchu, perched on a ridge in the Ande

The ancient Inca city of Macchu Picchu, perched on a ridge in the Andes Mountains of Peru, had been built at a high enough altitude that it often makes modern-day tourists from lower elevations sick with oxygen deprivation.

A: had been built at a high enough altitude that it often makes modern-day tourists from lower elevations sick with oxygen deprivation
B: had been built at so high of an altitude that it often makes modern-day tourists from lower elevations sick from oxygen deprivation
C: was built at a high enough altitude that modern day tourists from lower elevations often become sick with oxygen deprivation when visiting the city
D: was built at such a high altitude that modern-day tourists from lower elevations often become sick from oxygen deprivation when visiting the city
E: was built at so high of an altitude that it often makes modern-day tourists from lower elevations sick from oxygen deprivation
The ancient Inca city of Macchu Picchu, perched on a ridge in the Andes Mountains of Peru, had been built at a high enough altitude that it often makes modern-day tourists from lower elevations sick with oxygen deprivation.

A: had been built at a high enough altitude that it often makes modern-day tourists from lower elevations sick with oxygen deprivation--> the usage of past perfect is not required ,as it is already known explicitly that the construction of the site was done in the past.
B: had been built at so high of an altitude that it often makes modern-day tourists from lower elevations sick from oxygen deprivation--> the usage of past perfect is not required ,as it is already known explicitly that the construction of the site was done in the past.
C: was built at a high enough altitude that modern day tourists from lower elevations often become sick with oxygen deprivation when visiting the city-->sick with oxygen deprivation is wrong usage,although the problem with past perfect tense is rectified.
D: was built at such a high altitude that modern-day tourists from lower elevations often become sick from oxygen deprivation when visiting the city-->correct usage
E: was built at so high of an altitude that it often makes modern-day tourists from lower elevations sick from oxygen deprivation--> changes the meaning and leads to a fatal error.Modern day tourists are from the cities and not from lower elevation ..