Answer:
eons
Explanation:
these divisions contain anywhere from millions to billions of years
Alveoli are found in lungs and exchamge O2 and Co2 !!
so answer is last one !!
Professional antigen-presenting cells, such as phagocytes, are the first cells to encounter a pathogen (apcs). This means they have the ability to activate cells of the adaptive immune system.
<h3>What is meant by Pathogen?</h3>
- A pathogen is an organism that infects its host with disease, and the severity of the disease symptoms is referred to as virulence.
- Pathogens include viruses, bacteria, unicellular and multicellular eukaryotes, and a wide range of other organisms.
- The bone marrow of an average healthy adult generates 100 billion new neutrophils per day. Because there are so many neutrophils in the body at any given time, they are often the first cells to reach the site of an infection.
- Long thought to be a component of the innate immune system, complement has recently emerged as an important regulator of the adaptive immune response.
Therefore the correct option is D) can activate cells of the adaptive immune system.
To learn more about Pathogen, refer to:
brainly.com/question/1008643
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