Option 2: "2 and 3" is the correct answer.

Let`s analyze each statement:

1. "CO2 is a poisonous gas": This statement is incorrect. Carbon dioxide (CO2) is a naturally occurring gas that is essential for life on Earth. It is produced by processes such as respiration and combustion. While high concentrations of CO2 can be harmful and lead to suffocation in enclosed spaces, it is not generally considered a poisonous gas.

2. "CO2 is an acidic oxide": This statement is correct. CO2 is an example of an acidic oxide, which means it can react with water to form an acid. When CO2 dissolves in water, it forms carbonic acid (H2CO3), making the solution slightly acidic.

3. "CO2 turns lime water milky": This statement is also correct. Lime water is a solution of calcium hydroxide (Ca(OH)2), and when it comes into contact with CO2, it reacts to form calcium carbonate (CaCO3), which is insoluble and appears as a milky white precipitate.

In conclusion, statements 2 and 3 are both correct, making option 2 the correct answer.