14-identify the sentence that uses past perfect tense.
a.
before mary got home, sam ate dinner.
b.
by the time mary got home, sam had eaten dinner.
c.
when mary gets home, sam will eat dinner.
d.
by the time mary got home, sam was eating dinner.

B.  By the time Mary got home, Sam had eaten dinner.

Explanation:

The past perfect tense shows that something happened before another action in the past. This tense is formed with the helping verb had plus the past participle of the main verb. In this case, it is had eaten.  (Eaten is the past participle of the verb eat).  

honestly this is the biggest mood ever, i couldn't relate to this more

explanation:

the answer is b-$11,337.