Answer: New vaccines are offered each year because the virus changes.
Explanation: The flue viral strain constantly changes its genetic make up, a process called antigenic drift. As the virus replicates there are small changes that creates new strains which evolve to a completely different influenza virus requiring a new type of vaccine each year.
Rock A = It is a metamorphic rock that experienced tremendous heat and pressure due to massive, moving tectonic plates.
Metamorphic rocks are rocks that have been somewhat squished and transformed by heat and pressure. These rocks often have different layers as the rocks go through pressure and are literally look like rocks that have been piled up and then stuck together. The best indicator of this rock being a metamorphic rock is the wavy elongated stripes. The stripes are created from the different rock elements being pressed together over time.
Rock B = It is a sedimentary rock made primarily from lithification of organic material.
Sedimentary rocks are rocks that have been formed by different substances that come together due to the different weather conditions. The best indicator of this being a sedimentary rock is how the rock came together and looks like a bunch of shells were glued together.
Rock C = It is an igneous rock that was formed above Earth’s surface.
Most igneous rocks have smooth outer layers. These rocks are often made with solidified magma from volcanoes. The best indicator of this being an igneous rock is the indication of it being a solidified piece of magma.
Answer:
1. Form of oxygen that combines three oxygen atoms into each molecule is called ozone.
2. Most important weather phenomena occur in the troposphere.
Explanation:
1. The form of oxygen which combines with three oxygen atoms has a molecular formula as 
which is known as ozone.
Therefore, form of oxygen that combines three oxygen atoms into each molecule is called ozone.
2. The lower part of the atmosphere also known as troposphere is a layer where almost all the weather phenomena occurs.
This layer contains 99% of total mass of water vapor and aerosols. Also, it contains about 75% of atmosphere's mass.
Therefore, we can conclude that most important weather phenomena occur in the troposphere.
I think it would be in your white blood cells
