Read the following paragraph and choose the best topic sentence from the four options that follow.
Retirement may seem like a goal to strive for, but indeed it presents a challenge to us. Retirement like not having to go to work every day, traveling and living a life of leisure doesn't happen too often anymore. In our current economy, more and more individuals have no choice but to work well past the age of 65. The harsh reality is that most of those who cannot work-and even some of those who can-live in or close to poverty. Money aside, retirement also challenges us by forcing us to adjust to retired life. Work provides us not only with income but also with social interaction and a sense of purpose. So, our job is often an important part of our identity. When it ends, it's common to struggle with the loss of that identity.