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DNA is not a single stranded and does not have amino acids. Hence options, b & C are eiminated. Dna is a double helix structure containing nucleobase—either cytosine (C), guanine (G), adenine (A), or thymine (T)—as well as a monosaccharide sugar called deoxyribose and a phosphate group. 

The classical orchestra uses violin, flute, clarinet, cello, piccolo, Bass,...

The Berlin conference in 1884 was significant because it created rules on how European nations want to colonize Africa.

The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.

Hence, the given statement is true.

At any given speed, momentum is directly proportional to mass of an object.