Answer : The oxidizing element is N and reducing element is O.
is act as an oxidizing agent as well as reducing agent.
Explanation :
An Oxidizing agent is the agent which has ability to oxidize other or a higher in oxidation number.
Reducing agent is the agent which has ability to reduce other or lower in oxidation number.
The given reaction is :

act as an oxidizing agent.
The oxidation number of N in
is calculated as:
(+1)+(x)+3(-2) = 0
x = +5
And the oxidation number of N in
is calculated as:
(+1)+(x)+2(-2) = 0
x = +3
From the oxidation number method, we conclude that the oxidation number reduced this means
itself get reduced to
and it can act as an oxidizing agent.
act as a reducing agent.

The oxidation number of O in
is calculated as:
(+1)+(+5)+3(x) = 0
x = -2
The oxidation number of O in
is Zero (o).
Now, we conclude that the oxidation number increases this means
itself get oxidized to
and it can act as reducing agent.
Metals :-
Group 1A - Alkali metals ( highly reactive metals)
Non-metals :-
Group 17 - Halogens ( highly reactive non-metals )
The the last one, but isn't it c6h12o6?