IMO : B, I am seeing ||ism here, ' on the creation of ' and 'on construction and decoration of'

I had some doubt on the usage of 'they' and was thinking that it may be ambiguous, but then I realized that artisans' is in possessive form so only a possessive pronoun can refer to a possessive noun. 'They' can not refer to a possessive noun.So,we are left with the Buddha images and hence no ambiguity.

OA ?

In ancient Thailand, much of the local artisans' creative energy was expended for the
creation of Buddha images and when they constructed and decorated the temples that
enshrined them.

A. much of the local artisans' creative energy was expended for the creation of
Buddha images and when they constructed and decorated the temples that
enshrined them
lacks llelism and them creates ambiguity

B. much of the local artisans' creative energy was expended on the creation of
Buddha images and on construction and decoration of the temples in which they
were enshrined
correct
C. much of the local artisans' creative energy was expended on the creation of
Buddha images as well as constructing and decoration of the temples in which
they were enshrined
as well as shud connect two llel things...here it lacks llelism
D. creating images of Buddha accounted for much of the local artisans' creative
energy, and also constructing and decorating the temples enshrining them

images were not constructing and decorating the temples enshrining them.meaning altered

E. the creating of Buddha images accounted for much of the local artisans' creative
energy as well as construction and decoration of the temples that enshrined them

he creating of Buddha images were not accounted for construction and decoration of the temples that enshrined them........meaning alterd

am i correct in my soln....pls provide OA