[Grammar] By February 15, 1876, Bell __ an application for a patent for his 'improvement in tel

[tahasozgen]

By February 15, 1876, Bell __ an application for a patent for his 'improvement in telegraphy' at the United States Patent Office.

A) filed
B) has filed
C) was filed
D) had been filed
E) had filed

My answer is A. Key depicts E. There is no second verb there, so why past participle is chosen over the past simple? Thanks in advance.

 

[emsr2d2]

The key word here is "by". When reporting a past event with "by", we use the past perfect.

By 7am today, I had been awake for three hours.
By Tuesday, he had already done a full week's work.
By March, she had been on holiday five times!

 

[GoesStation]

Remember that questions require subject-verb inversion (and note the name of the tense). Ask why is the past perfect chosen?