the idiom under usage is
"So...That" we can eliminate any option that uses the idiom incorrectly
(B)
So poorly designed and executed by the marketing team
was a brand-building program
eliminate!(D) A brand-building program that was
so poorly designed and executed by the marketing team
that is missing- eliminateamong the option A/C and E
(A) A brand-building program was so poorly designed and executed by the marketing team that
A is the correct option!(C)
It was so poorly that a brand-building program was designed and executed by the marketing team
It was so poorly is ambiguous; what was so poorly? the answer option is not clear-
eliminate!(E)
Designed and executed so poorly by the marketing team was a brand-building program that
the option is in passive voice and gmat is not a huge fan of passive voice constructions
its always better to separate the modifier from the subject using a comma
the bolded part is the modifier-
wrong!