​Which ingredients are included in major types of herbicides? 

A)  ​soil inhibitors 
B)  ​carbamates and pyrethroids 
C)  ​contact and systemic chemicals 
D)  ​chlorinated hydrocarbons

Contact and systemic chemicals are the major types of herbicides, which include ingredients that either kill the plant on contact or are absorbed by the plant and kill it from the inside. Soil inhibitors (A) are not commonly used as herbicides, and carbamates and pyrethroids (B) are more commonly found in insecticides. Chlorinated hydrocarbons (D) were historically used as herbicides but have been mostly phased out due to environmental concerns.