Since it is necessary to emphasize the word and from the choices I would go with the one(s) with the quotation marks. B and C are the same, so it is both
<h2><em>It's a developed country with elaborate infrastructure, high quality of life, and technological innovation. Japanese learned to work and build efficiently and to focus on mental capital rather than material wealth. Japanese relied on economic liberalism and private industry to make the necessary technological leaps.</em></h2>
