<u>Answer:</u> The correct answer is Option 1.
<u>Explanation:</u>
Electrochemical cell is defined as the device that is used for the conversion of the chemical energy produced in a redox reaction into the electrical energy. In this cell, oxidation reaction occurs at anode and reduction reaction occurs at cathode.
For the given options:
<u>Option 1:</u> Oxidation reaction
Oxidation reaction is defined as the chemical reaction where a substance looses its electrons. The oxidation state of this substance gets increased and the substance gets oxidized.
<u>Option 2:</u> Reduction reaction
Reduction reaction is defined as the chemical reaction where a substance gains electrons. The oxidation state of this substance gets reduced and the substance gets reduced.
<u>Option 3:</u> Neutralization reaction
Neutralization reaction is defined as the chemical reaction where an acid reacts with a base to produce a salt and water molecule.
<u>Option 4:</u> Transmutation
This is defined as the process in which a nucleus is converted to another nucleus.
From the above information, at anode, oxidation reaction occurs. Thus, the correct answer is option 1.