A. Galaxy. is the correct answer. a galaxy is a colossal grouping of solar systems, and stars that slowly orbit each other, and other galaxies.
B. nebula. is incorrect. a nebula is a large collection of dust and small meteoroids.
C. light year. is not correct. light year- a large unit of distance, often used when measuring the distance between galaxies.
D. solar system. is incorrect. solar system- a group of planets and a star.
As blood enters the artery, the walls of these vessels expand and contract, which can be felt as the pulse where the arteries run close to the body surface.
It is common to detect the pulse with a few fingers placed on the radial artery on the wrist, or the carotid artery in the neck.
Because the walls of the arteries pulse whenever the left ventricle contracts, the pulse rate generally indicates the cardiac function, which is normally between 50 and 85 in a healthy adult.
Pulse is usually defined as the rhythmic dilation of the arteries due to flow of the blood caused by heart contractions. The measurement of the pulse rate can be used for the diagnosis of serious disease such as cardiac disease.
I just answered your other post with these questions. (:
Hello there.
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Sieve tubes are found in which vascular tissue?
</span><span>phloem tissue</span>
