Question

Herbicides are chemicals which control-
A) Insects
B) Fungi
C) Weeds
D) Nematodes

Answer 1

Hint: The herbicide suggests that it is related to herbs. Out of all the options, only weeds can be considered as herbs.

Complete Answer:
Herbicides are commonly known as weed killers, they are used to control unwanted plants. Herbicides can be selective which control specific weed species, while leaving the desired crop relatively unharmed. The other type can be non-selective which kills as well as all other crops, this can be used to clear the whole ground. Apart from these, other important bases of types include persistence, means of uptake, and mechanism of action. Products such as common salt and other metal salts were used historically as herbicides, however these have gradually been eliminated out of favour and are even banned in some countries due to their persistence and toxicity in soil. They may also contaminate groundwater. Use of herbicides has also been noted in warfare and conflict.
Modern herbicides are often synthetic, they mimic the natural plant hormones which interfere with the target plant’s growth. The term organic herbicide refers to herbicides intended for organic farming. Some plants produce natural herbicides, for example, the Juglans (walnut). Study of action of natural herbicides and other chemical interactions, is called allelopathy. Several weeds have developed herbicide resistance. Herbicides can be combined with different means of actions like integrated pest management used alongside other pest control methods.
Example of herbicides- 2,4-D; Acetyl coenzyme A carboxylase (ACCase); Enolpyruvylshikimate 3-phosphate synthase enzyme (EPSPS).

Thus, the correct answer is option C. Weeds

Note:Only weeds out of all the options can be killed by herbicides. However, weeds may develop herbicide resistance which leaves the herbicides useless.