Select the most appropriate option to fill in the blank.

I ______ home before she arrived.

had left

The most appropriate option to fill in the blank is had left.

The sentence is in the past perfect tense, which is used to describe an action that happened before another action in the past. In this case, the sentence is saying that I had left home before she arrived. This means that I left home at some point in the past, and then she arrived at a later point in the past.

The other options do not make sense in the context of the sentence.

• Left is the simple past tense of the verb leave. It cannot be used in this sentence because the sentence is describing an action that happened before another action in the past.
• Has left is the present perfect tense of the verb leave. It cannot be used in this sentence because the sentence is describing an action that happened before another action in the past.
• Have left is the present perfect tense of the verb leave, used with the plural subject "we". It cannot be used in this sentence because the subject of the sentence is "I".