Which of the following sentences would make the MOST effective concluding sentence for an essay on sibling rivalry?

Sibling rivalry hurts brothers and sisters.
Sibling rivalry creates competition, jealousy, and frustration in families.
Sibling rivalry causes many problems, but the worst is the frustration that it creates in families.
Sibling rivalry may be unavoidable, but by learning to value each individual's strengths, its harmful effects can be minimized.