In the following question, one part of the sentence may have an error. Find out which part of the sentence has an error and click the option corresponding to it. If the sentence is free from error, click the ‘No error’ option. Deforestation and over-exploitation by human beings (1)/ have adversely affected (2)/ environment. (3)/ No error (4)?

Option 3 : 3

The correct answer is option 3, i.e. the error lies in this part of the sentence.

• The noun ‘environment’ in the question lacks a determiner.
• The apt determiner in the context is ‘the’. 
• Determiners are used with nouns to give clarity to the noun. There exist many types of determiners in English. The major ones are articles (a, an, the), quantifiers (many, few, a little, much), numbers (one, two, thirty), possessives (my, our, your, whose), ordinals (second, first, last, next).
• Among the above-given determiners, 'the' becomes the apt determiner to suit the situation.
• In another sense, the given sentence is discussing an issue that will affect the environment. Even though the word environment is not mentioned before, the reader gets the idea that the speaker is talking about a particular entity. So, the definite article (the) is used. Here, the third part (3) is grammatically correct, because, we have two subjects- deforestation and over-exploitation. When the subject is plural, we have to go for a plural verb, which is have.

Correct sentence: Deforestation and over-exploitation by human beings have adversely affected the environment.