The correct answer is option-1, which states that only statement 1 is correct.

Statement 1 mentions that black soil becomes sticky when wet, which is accurate. Black soil, also known as regur soil or black cotton soil, is rich in clay content. When water is added to clay soil, it becomes sticky and compact.

Statement 2 states that black soil contains adequate nitrogen and phosphorus required for plant growth. However, this statement is incorrect. While black soil is renowned for its high fertility and is suitable for a variety of crops, it is not necessarily rich in nitrogen and phosphorus. The fertility of black soil is primarily attributed to its high clay content and ability to retain moisture, but additional nutrients like nitrogen and phosphorus may need to be supplemented through fertilizers or organic matter.

In summary, only statement 1 is correct, and statement 2 is incorrect. Therefore, option-1 is the correct answer to the question.