Which is the best practice for extracting value from object?

Which is the best practice for extracting property from object ,so that we can take its value?

We have the following code structure:

public List<Group> Activities { get; set; } 

In Group we have:

public List<Span> Spans { get; set; }

In Span class we have:

public object Activity { get; set; }

In method I have the following loop that I want to take from object Activity property Id from TV:

foreach (var activity in result.Activities)
        {
            if (activity.Spans != null)
            {
                foreach (var span in activity.Spans)
                {
                    if (span.Activity != null)
                    {
                        foreach (var propertyInfo in typeof(Spans).GetProperties())
                        {
                            if (propertyInfo.Name == "Activity")
                            {
                             //take value from activity
                            }
                        }
                    }
                }
            }
        }

In span.Activity we have : { Time = 123, EndTime = 123, Points = [ -48, -49 ], PointsStart = [ 0, -2, ], TV = [ { "time": "123", "Id": 7, "TitleId": 5 } ] }

I need to take from TV the Id property value and add it later to a list. Which is the best practice to do it and how?