85.
The answer is: C
Explanation
The correct option is C: Seven years.
According to Section 82 of the Indian Penal Code (IPC), nothing is an offence which is done by a child under seven years of age. This means that a child below this age cannot be held guilty for any crime, as he or she is presumed to be incapable of understanding the nature and consequences of his or her actions. This principle is based on the doctrine of 'doli incapax', which means incapable of crime.