The answer is D. In a
geological era, when the plants and animals
in the then environment die, they get buried
in sediments. These sediments are covered
by other sediments of another geological
time within which are the remains of dead species
of the then geological era. These sediments from different geological times have different properties hence
form visible strata that can be studied to identify the kind of environment in the then geological time. Their
fossils can also be studied to identify
the kind of species that roamed the earth during the time.
Reflecting telescopes
Telescopes that use lenses are called refracting telescopes. The other type uses mirrors to focus the light of the image. These telescopes are called reflecting telescopes. Refracting telescopes use lenses to bend the light to a specific focal point such that the object will be magnified to the viewer.
light microscope
Optical instruments are based on optics. They use mirrors and lenses to reflect and refract light and form images. The light microscope and telescope use convex lenses and mirrors to make enlarged images of very tiny or distant objects. A camera uses a convex lens to make a reduced image of an object.
Refracting telescopes use lenses to focus the light, and reflecting telescopes use mirrors. I'll talk first about refracting ones. Refracting telescopes work by using two lenses to focus the light and make it look like the object is closer to you than it really is. Both lenses are in a shape that's called 'convex'.
the reflector telescope uses a mirror to gather and focus light. All celestial objects (including those in our solar system) are so far away that all of the light rays coming from them reach the Earth as parallel rays. Because the light rays are parallel to each other, the reflector telescope's mirror has a parabolic shape. The parabolic-shaped mirror focusses the parallel lights rays to a single point. All modern research telescopes and large amateur ones are of the reflector type because of its advantages over the refractor telescope.
Advantages
Reflector telescopes do not suffer from chromatic aberration because all wavelengths will reflect off the mirror in the same way.
Support for the objective mirror is all along the back side so they can be made very BIG!
Reflector telescopes are cheaper to make than refractors of the same size.
Because light is reflecting off the objective, rather than passing through it, only one side of the reflector telescope's objective needs to be perfect.
Disadvantages
It is easy to get the optics out of alignment.
A reflector telescope's tube is open to the outside and the optics need frequent cleaning.
Often a secondary mirror is used to redirect the light into a more convenient viewing spot. The secondary mirror and its supports can produce diffraction effects: bright objects have spikes (the ``christmas star effect'').
hope this helped!
Answer:
The heart valves
Explanation:
The heart valves prevent blood from flowing in the wrong direction in the heart. The valves are held in the proper place because of the chordae tendinae.
Answer:
Gulls, since they are the only predators shown for the green crabs.
