A local factory has been dumping chemicals into a nearby river that resulted in the death of many aquatic dwelling organisms. This is an interaction between which to spheres? PLZ HELP ASAP

Which of these describes the rate of this chemical reaction? h2 + cl2 → 2 hcl a. an increase in the concentration of hcl and h2 with time b. an increase in the concentration of hcl with time c. an increase in h2 and cl2 with time d. a decrease in hcl and cl2 with time