What blood component is primarily responsible for destroying disease-causing pathogens?

The correct answer is leukocytes, also known as white blood cells. These cells play a critical role in the immune system by identifying and eliminating pathogens such as bacteria, viruses, and fungi. Leukocytes have various types, including neutrophils, lymphocytes, monocytes, and eosinophils, each with specific functions in the immune response. For example, lymphocytes are pivotal in targeting specific pathogens and forming memory cells for quicker responses in future infections.

Platelets are primarily involved in blood clotting and do not have a role in combating pathogens. Erythrocytes, or red blood cells, are responsible for transporting oxygen throughout the body and do not participate in immune defense. Plasma, the liquid portion of blood, carries water, nutrients, hormones, and waste products, but it is not directly involved in pathogen destruction. Thus, leukocytes are the key component in the bloodstream for fighting infections and maintaining overall health.