Provides the support for the bases in the structure of DNA.

A. Phosphate
B. Sugar
C. both phosphate and sugar

C. both phosphate and sugar

Explanation:

DNA is made up of two strands, each made of nucleotides. Each nucleotide, in turn, is composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. There are four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). DNA takes a double helix shape, like a spiral staircase where the sides are chains of sugars and phosphates connected by steps, which are the nitrogenous bases.

C. BOTH PHOSPHATE AND SUGAR

Explanation:

The four nitrogenous bases that form the DNA are adenine, guanine, cytosine, thymine. Cytosine and thymine are pyrimidines while adenine and guanine are categorized as purines. These bases forms the DNA double helical structure through weak hydrogen bonds between the two opposite strand of the DNA and they complement each other as adenine is always paired with thymine by two hydrogen bonds and cytosine with guanine with three hydrogen bonds. In the DNA, nitrogenous bases are supported by the deoxyribose sugar and phosphate group. They are joined together by covalent bonds called phosphodiester bonds between the sugar of one nucleotide and the phosphate group of the other. This provides for the double helical structure of DNA.

it's all four options.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.