Official Explanation In this question, you need to identify the subject-verb agreement error. The subject of the sentence is "the company's policy".
(A) along with sponsoring a number of charitable events,
are an example of the company's
(B) as well as to sponsor a number of charitable events,
is an example of the company's
(C) as well as sponsoring a number of charitable events,
are an example of the company's
(D) and sponsoring a number of charitable events,
is an example of the company's
(E) and sponsors a number of charitable events,
are an example of the company's
So we are left with B & D
We are talking about the company's contributions. So ideally company is the once sponsoring the events. --Meaning
(B) as well as
to sponsor a number of charitable events,
is an example of the company's
Here employees are sponsoring the events. (D) and sponsoring a number of charitable events,
is an example of the company's
Hence D is the best fit