Answer:
Add a comma after "environmentalism".
Explanation:
Punctuation is the most important part of a sentence. any misplacement or elimination of punctuation marks can change the entire meaning of a sentence.
In the given sentence, the grammatical error is in the punctuation mark. A comma (,) should be placed after the word "environmentalism."
So, the sentence with the correct punctuation mark would be:
<em>"Henry David Thoreau, often known as the father of environmentalism, wrote the book entitled Walden."</em>
The comma is placed after the word "environmentalism" because the phrase "often known as the father of environmentalism" is a modifier.
So, the correct answer is the last option.
