Answer : The correct option is, (1) 0
Explanation :
Oxidation state or oxidation number : It represent the number of electrons lost or gained by the atoms of an element in a compound.
Oxidation numbers are generally written with sign (+ and -) first and then the magnitude.
When the atoms are present in their elemental state then the oxidation number will be zero.
As per question, 'Mn' atom is a free element that means it is present in their elemental state then the oxidation state will be zero.
Hence, the correct option is, (1) 0