Answer: 5. Clearly, there are many benefits of newborn babies being breast fed.
Step-by-step explanation:
The topic sentence is the one that states the main idea of the text. In this example, the first sentence presents the different choices available regarding feeding a baby, which are breast-feeding or using formula milk. The next sentences provide evidence of the different benefits of breast-feeding. Only in the last sentence, the topic idea is presented, by claiming that breast-feeding is the best option.