I would say 4, it seems a lot clearer than the other answers to me.
Answer:
1.
an exchange of diverging or opposite views, typically a heated or angry one.
2.
a reason or set of reasons given with the aim of persuading others that an action or idea is right or wrong.
While low-carbohydrate diets have become increasingly popular as a potential, more effective method of weigh loss that has, as well, other health benefits, doctors believe, based on the available research literature, that these diets carry potential long-term health risks. The research literature indicates: first, that this type of diet is highly effective for short-term weight loss but the long-term effectiveness is not significantly greater than other diets: that the extra health benefits are unknown so far, and finally, that there is higher potential for negative health outcomes due to an increased consumption of saturated fat. More research is needed, but this three points seem to conclude on the importance of following a balanced, moderate diet appropiate for the individual.
