Buddha images and when they constructed and decorated

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

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

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

D. creating images of Buddha accounted for much of the local artisans’ creative
energy, and also constructing and decorating the temples enshrining them

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

can someone help me in explain what "that" refers in option E and what 'which" refers to in option B
and please explain why you eliminate each options!