Option (a) is correct.
A reducing agent is the one which loses electrons to other substance.
Here, Zn has oxidation number 0 in the L.H.S of the equation, but on R.H.S its oxidation number is +2 i.e. it Zn has donated two of its electrons to

.
Hence, Zn is the reducing agent here.
Answer:
Explanation — This page looks at the oxidation of alcohols using acidified sodium or ... of sodium or potassium dichromate(VI) acidified with dilute sulfuric acid. ... The electron-half-equation for this reaction is as follows: ... To do that, oxygen from an oxidizing agent is represented as [O]. ... Article type: Section or Page.
<span>Kwang Jeon observed that Amoeba had been attacked by a bacterial infection, and lots of the Amoeba had
died. However, some survived and continued to reproduce. After investigating the remaining
Amoeba and their offspring, he noticed they were very healthy. He thought maybe they were able to
fight off the bacteria, but instead, he found they were still infected with the bacteria but were not
dying. The bacteria were no longer making the Amoeba sick. Then, he killed off the bacteria using
antibiotics and was surprised to see that the Amoeba also died. It seemed the Amoeba and bacteria
had formed a relationship in which they both needed each other to survive. After researching, Jeon
found that the bacteria made a protein that the Amoeba needed to survive. </span>
What occures is that the solution is know considered to be alkali, OH- ions react with the H+ ions from acids.
hope that helps :)