To understand the reduction of nitrobenzene to aniline, let's examine each option given in the question.


This is a catalytic hydrogenation reaction where hydrogen gas (H2) is passed over a nickel catalyst (Ni). The hydrogen gas gets absorbed on the surface of the catalyst, and the resulting hydrogen atoms react with the nitrobenzene molecule, leading to the reduction of the nitro group (-NO2) to an amino group (-NH2). This reaction is also commonly known as the "Haber process" or "Sabatier process."


This is a reduction reaction using tin (Sn) and hydrochloric acid (HCl). The tin acts as a reducing agent, which donates electrons to the nitrobenzene molecule, leading to the reduction of the nitro group to an amino group. The hydrochloric acid helps in the reaction by providing an acidic medium. This reaction is known as the "Clemmensen reduction."


This reaction involves the use of zinc (Zn) and sodium hydroxide (NaOH). However, this combination is not suitable for the reduction of nitrobenzene to aniline. It may lead to other undesired products or no reaction at all.


This is a powerful reducing agent called lithium aluminum hydride (LiAlH4). It is capable of reducing a wide range of functional groups, including the nitro group. In the presence of LiAlH4, nitrobenzene undergoes a reduction reaction, converting the nitro group to an amino group.


Based on the above analysis, it can be concluded that options I and II are valid methods for reducing nitrobenzene to aniline. Option IV, which involves the use of LiAlH4, is also a valid method. However, option III is not suitable for this specific reduction reaction. Therefore, the correct answer is option B, which includes options I and II as valid methods for the reduction of nitrobenzene to aniline.