The number of ways of choosing 10 objects out of 31 objects of whic...

The number of ways of choosing 10 objects out of 31 objects of which 10 are identical and the remaining 21 are distinct, is
(2019 Main, 12 April I)
(a) \( 2^{20}-1 \)
(b) \( 2^{21} \)
(c) \( 2^{20} \)
(d) \( 2^{20}+1 \)