-  advice is Singular Uncountable Noun. So, an will not be there.

The error in the given sentence is in Part 2 - "to give an advice to those." The correct phrase should be "to give advice to those." The correct sentence should read: "It is not my business to give advice to those who are not sensible enough to deal with their own problem."

Here is a detailed explanation:

• Part 1 - "It is not my business" is a correct and complete sentence fragment. It conveys the meaning that the speaker does not want to involve themselves in the situation.

• Part 2 - "to give an advice to those" is incorrect. The article "an" is unnecessary before the word "advice." "Advice" is an uncountable noun and does not require an article. The correct phrase should be "to give advice to those."

• Part 3 - "who are not sensible enough" is correct. The phrase "not sensible enough" means that the people being referred to lack the necessary good judgment or intelligence to handle their problem.

• Part 4 - "to deal with their own problem" is correct. It conveys the meaning that the people being referred to are expected to handle their own problems without the intervention of the speaker.

In conclusion, the correct sentence is: "It is not my business to give advice to those who are not sensible enough to deal with their own problem." Option B is the correct answer as it identifies the error in Part 2.