If we want to write a balanced answer for the question below, it's important to make our balanced view very clear in the introduction.
Here's the question again:
In some countries, many more people are choosing to live alone nowadays than in the past. Do you think this is a positive or negative development?
Here's my 'balanced opinion' introduction:
In recent years it has become far more normal for people to live alone, particularly in large cities in the developed world. In my opinion, this trend is having both positive and negative consequences in equal measure.
Notice that I wrote two sentences as usual. The first sentence introduces the topic by paraphrasing the question statement, and the second sentence makes my opinion very clear.