Question

Diener discovered
A. Free infectious protein
B. Free infectious DNA
C. Free infectious RNA
D. Bacteriophage.

Answer 1

Hint:Dr. Diener extracted the viroid from spindle tuber diseased potatoes. Spindle tuber disease has been familiar for more than 50 years, but previously it was considered to be induced by a virus. Like a virus, the potato disease viroid is self-replicating in living cells.

Complete answer:
To answer this question, first, we need to know about Diener. Theodor Otto Diener is the Swiss-American plant pathologist who was born February 28, 1921. In 1971, he discovered that the causative agent of the potato spindle tuber disease is not a virus, but a different agent, which contains a short strand of single-stranded RNA without a protein capsid, that is much tinier than the other smallest viruses.
 The phenomenon of a small infectious RNA was first reported by T.O. Diener As a distinct class of pathogens that do not encode any protein and lack a capsid. Hence it is called free infectious RNA.

Thus, the correct option is C. i.e. Free infectious RNA.

Note:In 1971, T.O.Diener found out viroids which are infectious agents which consist of much less molecular weight RNA without any protein coat. These are smaller than viruses that cause potato spindle tuber disease, chrysanthemum stunt etc. Whether viroids occur in animal cells is still uncertain.