In the following reaction the reason why meta-nitro products also formed is:
Option: 1 Formation of anilinium ion
Option: 2 -NO2 substitution always take place at meta-position
Option: 3 low temperature
Option: 4 -NH2 group is highly meta-directive
Direct nitration of aniline yields tarry oxidation products in addition to the nitro derivatives. Moreover, in the strongly acidic medium, aniline is protonated to form the anilinium ion which is meta directing. That is why besides the ortho and para derivatives, significant amount of meta derivative is also formed.
Therefore, Option 1 is correct.
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