The value of ${}^{21}C_1 - {}^{10}C_1 + {}^{21}C_2 - {}^{10}C_2 + {}^{21}C_3 - {}^{10}C_3 + {}^{21}C_4 - {}^{10}C_4 + \ldots + {}^{21}C_{10} - {}^{10}C_{10}$ is\\
(1) $2^{21} - 2^{11}$\\
(2) $2^{21} - 2^{10}$\\
(3) $2^{20} - 2^{9}$\\
(4) $2^{20} - 2^{10}$