What is the study of the spectra produced from the emission and absorption of electromagnetic radiation?
(a) study of absorption spectrums
(b) study of emission spectrum
(c) nanotechnology
(d) spectroscopy

The correct option is (D).

Explanation:

Spectroscopy is defined as study of interaction between the matter and electromagnetic radiations. It is also known as study emission and absorption  spectra.

Absorption spectrum : When the photons of light are absorbed by an electron by which it jumps to higher energy level and the dark line will appear which corresponds to absorption of an energy of light of certain wavelength. the spectra of black line is obtained.

Emission spectrum : When an electron moves to lower energy level from higher energy level ,energy is emitted and this energy emitted corresponds to certain wavelength of light . If the wavelength of is lying in visible region of electromagnetic wave a colored spectra of emission is obtained.

Nanotechnology : It is a branch of science and technology which studies the the matter at microscopic level  scaling from 1 nano-meter to 100 nano-meter.

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.