Checking the dining areas of an eating establishment for evidence of flaking paint broken lightbulbs and wood damage will reduce the chances of

Checking the dining area of an eating establishment for evidence of flaking paint, broken light bulbs and wood damage will reduce the chances of PHYSICAL CONTAMINATION OF FOOD. Many food safety guidelines had been produced by the Food and Drug Administration to ensure public food safety in restaurants and other public eateries. 

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.