If $I(m, n) = \int_0^1 x^{m-1}(1-x)^{n-1}\,dx$, $m, n > 0$, then $I(9, 14) + I(10, 13)$ is\\ (1) $I(19, 27)$\\ (2) $I(9, 1)$\\ (3) $I(1, 13)$\\ (4) $I(9, 13)$