The system of linear congruence x ≡ ai (mod ni) with gcd(ni, nj) = 1 for i ≠ j has a simultaneous solution which is
1
distinct modulo ni's for 1 ≤ i ≤ ∞
2
unique modulo ni's for 1 ≤ i ≤ r
3
unique modulo ni's for 1 ≤ i ≤ ∞
4
distinct modulo ni's for 1 ≤ i ≤ r