Which one of the following integrals is NOT an improper integral?
1
\(\mathop \smallint \limits_0^\infty \frac{{dx}}{{1 + {x^2}}}\)
2
\(\mathop \smallint \limits_{ - \infty }^0 {e^x}dx\)
3
\(\mathop \smallint \limits_{ - 1}^1 \frac{{dx}}{{{x^2} - 2}}\)
4
\(\mathop \smallint \limits_{ - 2 }^2 {\frac{1}{x}}dx\)