a. vitamins.
b. everyday.
I'm not 100% sure on b. but a. has to be vitamins.
1st of all arteries have a thick walls while veins have have a thin wall
Answer to why arteries have thick walls: arteries have thick walls because blood flows inside them with high pressure and with a high speed
In order from least to most dense, it must be: C, B, A and D. Seawater with high temperature causes an object to float, while seawater with low temperature sinks or is denser than high temperature. Salinity is also a factor to determine density; the higher the salinity, the denser the water. In terms of depth, it seems that sample D is the deepest part while sample A is the shallowest. This is determined because temperature drops significantly with depth.
The purines have two rings in their structure while the pyrimidines have hust one
