Hint: To answer this question we will start with understanding the term spectrum and its types which are given in the question i.e. Absorption spectrum, Emission spectrum, etc. Starting with the definition of the spectrum which means a range of waves such as radio waves or light waves, or a band of colours that can be obtained from white light by dispersion.
Complete Step by step solution:
Now we will discuss the types of the spectrum and its category. The spectrum can be categorized into absorption, emission, and continuous spectrum.
Continuous spectrum means the spectrum which consists of or appears all wavelengths. Such a spectrum can be observed when white light passes through a prism it gets dispersed into various bands of colour. Example of the rainbow.
Absorption spectrum means the spectrum such as electromagnetic radiation that is when passing through a medium, radiation of a certain range of frequencies is absorbed. During the absorption spectrum, the intensity of the spectrum decreases as some frequencies of radiation get absorbed.
Emission spectrum are those in which when radiation such as electromagnetic radiation when interacts with atoms and molecules then the electrons In that atom which are in the higher energy state make the transition to the lower emery state by emitting some radiations hence results in the emission spectrum.
Now in the case of sodium lamp which is an electrical lamp in which we first vaporize the sodium such that atoms of sodium atoms get excited and after due to de-excitation it emits the radiation due to attain stability which results in visible light, hence results in the emission spectrum.
Hence, option (B) is the correct answer.
Note: The sodium vapor lamp uses sodium in an excited state to produce light having a wavelength of about $500-600 nm$. It is a type of gas discharge tube which is found into two types such as high pressure and low-pressure vapor lamps.