The main trick is that the correct meaning intends to modify the clause "
the museum administration has begun to offer more interactive displays".
in A: Grammatically, "
which are" can correctly modify "
displays", and "
have been proven" is the correct verb for "
strategies".
in B: Grammatically, "
which are" can correctly modify "
displays", and "
has been proven" is the correct verb for "
strategy".
However, both are incorrect because the whole clause should be modified, not the noun "
displays", so incorrect meaning.
in C: the option tried using "
which is" to modify the whole clause, and used "
has proven" as a correct verb for "
strategy".
however, "Which" can't modify a whole clause, but can only modify nouns, so incorrect grammar.
in D: appositive phrase starting with the noun "
strategies" is used.
However, appositive phrase can only modify the precedent noun "
displays", but not the whole clause, so incorrect meaning.
in E: absolute phrase "
a crowd-drawing strategy that ..." is used, and
has been proven" is the correct verb for "
strategy".
Absolute phrase can modify the whole precedent clause, which is the correct intended meaning.