Among the electrolytes $$Na_{2}SO_{4},\ CaCl_{2},\ Al_{2}(SO_{4})_{3}$$ and $$NH_{4}Cl$$, the most effective coagulating agent for $$Sb_{2}S_{3}sol$$ is

A

$$Na_{2}SO_{4}$$

B

$$CaCl_{2}$$

C

$$Al_2(SO_4)_3$$

D

$$NH_4Cl$$