Answer: A) Biosphere Explanation: A biosphere is the sum of all the ecosystems established on planet Earth. An ecosystem is an area in which the plants and animals all interact to create a living environment. Therefore ecosystem is a smaller unit of earth, all ecosystems together form the earth.

Answer: D) 4.3 light-years away Explanation: The nearest stars to Earth are in the Alpha Centauri triple-star system, about 4.37 light-years away. One of these stars, Proxima Centauri, is slightly closer, at 4.26 light-years.   Of all the stars closer than 15 light-years, only two are spectral type G, similar to our sun: Alpha Centauri A and Tau Ceti. The majority are M-type red dwarf stars.   Only nine of the stars in this area is bright enough to be seen by the naked human eye from Earth. These brightest stars include Alpha Centauri A and B, Sirius A, Epsilon Eridani, Procyon, 61 Cygni A and B, Epsilon Indi A and Tau Ceti.

Answer: D) Shadow Explanation:

Answer: B) Uranium Explanation: Uranium is not a fossil fuel whereas coal, petroleum and natural gas are all natural resources. Fossil fuels are hydrocarbons, primarily coal, fuel oil or natural gas, formed from the remains of dead plants and animals. In common dialogue, the term fossil fuel also includes hydrocarbon-containing natural resources that are not derived from animal or plant sources

Answer: A) Nucleus Explanation: Nucleus serves as the control center for cell metabolism and reproduction.

Answer: B) Hard copy Explanation: Hard copy is the output which is printed by the computer.

Answer: B) commercial taxes Explanation:

Answer: C) intensity of illumination Explanation: The lux (lx) is the SI derived unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square meter.