Answer:
a.
Explanation:
It decreases from the aorta to the vena cava.
Specific excretory organs are absent in unicellular organisms belonging to the<u> phylum Porifera.</u>
The organisms of the phylum Porifera are classified under the kingdom Animalia and they lack specific organs in their bodies.
The word "Porifera" refers to pore-bearing organisms.
These animals have loosely organized cells and are found in freshwater marine ecosystems.
On their body, a large number of pores - Ostia - are present which perform various functions such as excretion.
However, respiratory gases and waste materials are exchanged through a diffusion process.
Moreover, in them, reproduction takes place through fragmentation and budding.
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Bal stands for Bronchoalveolar lavage. Bal is a process in which a bronchoscope is passed through the mouth and then into the lungs. Fluid is squirted into a part of he lung and collected for examination. Lung diseases can be found from the process of bal.
