Concept:For century years, only those divisible by 400 are leap years.Explanation:A century year must be divisible by 400 to be a leap year.1900 is a century year but is not divisible by 400 (1900 ÷ 400 = 4.75).Thus, 1900 is not a leap year.The other options (800, 1600, 2000) are all divisible by 400, so they are leap years.Answer:A. 1900