______ attack all kinds of intruders in the body. Group of answer choicesNatural killer cells T-cells Blood  cells None of the above

To answer the question, we need to identify which cells attack intruders in the body. The options given are natural killer cells, T-cells, blood cells, and none of the above.

First, let's consider natural killer cells. These cells are part of the immune system and are known for their ability to recognize and destroy infected or abnormal cells in the body. They play a crucial role in defending against viruses and certain types of cancer.

Next, we have T-cells. T-cells are a type of white blood cell that are responsible for coordinating the immune response. They can recognize specific antigens on infected cells and trigger an immune response to eliminate the intruders. T-cells are essential for adaptive immunity and play a vital role in fighting off infections.

The option "blood cells" is quite broad, as blood contains various types of cells, including red blood cells, white blood cells, and platelets. While red blood cells and platelets have important functions in the body, they are not directly involved in attacking intruders. However, certain types of white blood cells, such as natural killer cells and T-cells, are responsible for this defense mechanism.

Based on the information provided, it can be concluded that both natural killer cells and T-cells attack intruders in the body. Therefore, the correct answer is "Natural killer cells and T-cells."