The following question was given in a book as an autocad assignment. The section depicted in the diagram is not a counter-bore or a spot face hole. But the professor is telling that the hole is a counter bore.
This is the correction suggested by the professor in the blue pen. This is the section view of the front view along of A-A line. Is the correction correct as I argued that this not true.
You are correct. There isn't enough information to suggest a counterbore.
Figure 1. Part view from rear.
Figure 2. Section view.
The original drawing is ambiguous. There is no hidden line showing that the individual holes are counter bores. The portion of the drawing that is cut out also is in the area where the other portion of the counter bore would be shown. It could be clearer.
All of that being said, there is one way that you could assume that each of the holes has a counter bore: Look at where the dimensions are drawn from. The dimension shown in the cut out is drawn from the centerline of the hole. This would only make sense if it was dimensioning the radius of a counter bore. The dimension is connected to the centerline of the small hole even if the only dimension is to the outside of the part.
The end result is that the original drawing could be clearer, but without a counter bore, the dimension given doesn't make sense.