A sentence which contains a verb in the simple past tense is C. She obeyed her father.
<em>Simple past tense</em> is used to depict an action that existed or happened before now. It is the basic form, action duration is not important as it can be in the distant past or recent past.
Certain time expressions are associated with a simple past tense that is:
Frequency - I sometimes ate those chips
A definite point in time- we went to the mall last week
An indefinite point in time- when I was a child, I loved playing hide and seek.
Hence, in the above sentence, it uses a <em>definite point in time</em> "obeyed her father."
How about you start writing an outline first, you can name the benefits of recycling, also, how by separating, she can be more organized with the garbage. Make sure you use examples.