Questions

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. 

To make steel, iron ore is first mined from the ground. It is then smelted in blast furnaces where the impurities are removed and carbon is added.

In simple, steel is iron alloyed with carbon, usually 0 - 2%.

‘ought’ represents advice, ‘would’ represents strong possibility of an event here. ‘would have’ will be the correct grammatical expression here. The sentence expresses that the accused was not sent to jail because of one witness.

The main motive behind dealer incentives is to give the products at some low price for the dealers who take the products in bulk and maintain good selling of these products.