"Not all cops are bad" is correct. The first example is misleading and would cause confusion in the reader
You didn't give the options for techniques, but I will explain to you what rhythm in a poem is.
Simply put, rhythm can be defined as the beat and velocity of a poem. Rhythm is created by a continuous pattern of 'stressed and unstressed' syllables in a line or verse of your poem. Rhythm can help to strengthen the application of words and ideas in a poem.
Answer:
It is either C or E, but definitely not A, B, or D
I'm not 100% on if it's C or E though, so I don't want to steer you wrong