The correct answer is: D. breathing
Lymphatic system is an open system that does not have a central pump (such as heart in the circulatory system), so the flow of the lymph is different than blood flow. Transport and movement of the lymph are slow and sporadic. Lymph flow occurs thanks to:
• peristalsis – contraction and relaxation smooth muscle tissue,
• valves- so that lymph doesn’t flow backwards along the vessels
• contraction of adjacent skeletal muscle .
They are used to feel around and to capture prey. They extent their tentacles to capture prey, and use their nematocysts (nettle-like cells on their tentacles) to pierce and poison their prey. Hope that helps!
Saliva is not excreted by the human body.
Carbon dioxide is excreted by respiration.
Urea is excreted by urine.
Salt is excreted by sweat.
The correct answer is option C, that is, viruses.
An infection occurs when a foreign species moves inside the body of an individual and causes harm. The species utilizes the body of that person to reproduce, sustain itself, and colonize. These infectious species are called pathogens. The examples of pathogens are viruses, bacteria, prions, and fungi.
Of the given options, viruses are the smallest infectious agent. The viruses are basic particles, which must infect a host cell to reproduce and develop. Viruses utilize the host cells metabolic machinery to double themselves.
