In His Flight Simulator Study Investigating the Potential Causes of a Series

In his flight simulator study investigating the potential causes of a series of airplane crashes,Conrad Kraft concluded that the crashes appear to have been caused by a visual illusion created when approaching a city:

A) at night that has lights behind it that slope upward.
B) at night under conditions of poor visibility.
C) at night that has lights in front of it that slope upward.
D) during the day under conditions of poor visibility.