问题
One of the types of cost estimation is Order of Magnitude This estimate
A:Is performed when detailed information is available
B:Is performed when little if any information is available
C:Is used in the beginning of the project conceptualization
D:B and C
B:Is performed when little if any information is available
C:Is used in the beginning of the project conceptualization
D:B and C
正确答案是：
