Which statement is true about the effect of red tide or algal bloom on the ecosystem? A) produces toxins that can harm aquatic life
B) decreases amount of oxygen for aquatic producers
C) decreases aquatic food source for humans
D) all of the above

9. technology can bring both good and bad things. building a vertical farm can increase food supplies in cities (good), but it may cause unemployment in rural areas (bad). give another example of both the good and bad sides of a technological advancement (5 noints)