The correct answer is C. lens. Lens is a convex sealed capsule containing a clear fluid and focuses light to the back of the eye. Iris is the colored part of the eye that contracts and expands under influence of ciliary muscle. Retina is the inner surface of back of eye. Cornea is a transparent and curved surface of eye that helps to focus light.
The correct answer is option A, that is, placer deposits.
The concentration of heavy deposits known as the placer deposits are produced by the gravitational action, generally found in streams. The minerals that take place as placer deposits comprise copper, gold, magnetite, cassiterite, and copper.
The formation of placer deposits takes place when the metal-bearing rock on land is weathered and the generated debris is washed down to the sea by the rivers. Further by the action of waves, currents, and rides the particles of heavy metal gets amassed to produce mineral sand deposits. These generally occur as beach deposits.
The answer is Paramecium.
The paramecium is a unicellular ciliated protozoan. They are
often found in fresh water and brackish water areas. They have the elongated
shaped that looks like a rod and has the color violet under the stain because it signifies that it is positive.
