A Census Town (CT) is defined by the Census of India based on certain criteria:
(A) The minimum population size for a Census Town is 5000. This is a clear requirement for being classified as a Census Town. Hence, statement (A) is correct.
(B) The population density must be at least 400 persons per square kilometer to qualify as a Census Town. This is part of the criteria set by the Census of India. Therefore, statement (B) is correct.
(C) A Census Town must have at least 55 percent of the male working population not engaged in agriculture. This is a key criterion, but the statement is incomplete; the percentage criterion refers to the male working population, but it's primarily about non-agricultural work. Therefore, statement (C) is incorrect.
(D) The population density of at least 250 persons per square kilometer is a characteristic of towns but does not meet the threshold for a Census Town, where it is 400 persons per square kilometer. Hence, statement (D) is incorrect.
Conclusion: The correct statements are (A) and (B).