A parallel structure means that withing the sentence the same structure/scheme is used everywhere. So the correct answer is B. A cannot be correct as you have "BEING honest", "BEING courageous" and then just "compassionate". BEING was deleted. C is also incorrect as you have "BEING honest" and then just nouns "courage" and "compassion" - the structure has changed. It is the same case with D - "IS honest", "IS courageous" and then just "compassionate", without IS. And B is correct because we have three nouns "honesty", "courage", "compassion" - the structure remains the same.
