Answer : The correct option is, 
Explanation :
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In the oxidation reaction, the oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Oxidizing agent : It is defined as the substance which has ability to oxidize the other substances by gaining electrons.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In the reduction reaction, the oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
Reducing agent : It is defined as the substance which has ability to reduce the other substances by losing electrons.
From the given options, we conclude that
(1) 
(2) 
(3) 
The reaction 1, 2 and 3 shows the reduction reaction. So, it requires a reducing agent.
(4) 
The reaction 4 shows the oxidation reaction. Therefore, it requires an oxidizing agent.
Therefore, the correct option is, 