150.
C is true because zeolite is replacing STPP in detergent production. See line 3 of paragraph 2.
A = untrue as zeolite does not harm aquatic ecological systems. See line 1 of paragraph 2.
B = also not true as zeolite reduces the foam problems. See the last line in paragraph 2.
D = untrue because it was only considered after STPP began to decline in 1980. See line 2 paragraph 1