Select the option that contains a grammatical error in the underlined portion. 

There are no tables at the classroom. 

The correct answer is "There are no tables at the classroom."Key Points

• The error lies in the last part of this sentence. The word "at" is erroneous.
• This is an error of prepositions. The placement of "at" preposition is inaccurate.
• Let's understand the implication of the incorrect preposition:
• At: in the direction of or towards somebody/something.
  • Example: Somebody threw a shoe at the chief minister.
  • Example: I was looking at the beautiful flowers.
• Now, let's understand the implication of the incorrect preposition:
• In: that is located inside or within; expressing the situation of something that is or appears to be enclosed or surrounded by something else.
  • Example: He was in his car.
  • Example: She was dressed in her best dress.
• Therefore, "at" should be changed to "in" because it is inaccurate.

Therefore, the answer is option 4.

Correct sentence will be: : There are no tables in the classroom. 

Additional Information

• Let's know more about prepositions:
• Prepositions are words or phrases that are used in front of a noun, pronoun, or noun phrase to indicate time, place, location, direction, or spatial relationships, or to present an object.
• A preposition is typically placed before the word or phrase it refers to, or the preposition's object.
• The Preposition should be followed by an object form of the Pronoun.
  • Examples: "in," "at," "on," "of," and "to."