This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
True regarding mortality rate: 
Select and explain. 
A. Little important information about changing pattern of disease, B. Usually standardization for age and sex, C. Crude death rate includes only deaths from death certificate data, D. Standardization mortality ratio is the unexpected number of death divided by observed number of deaths in a specific group
A: Little important information about changing pattern of disease
Answer: A: Little important information about changing pattern of disease 
Explanation: (Refer: K. Park’s Textbook of Preventive and Social medicine, 24th  edition, pg no: 63
Standardized mortality ratio

Standardized mortality ratio is the ratio of observed deaths by expected number of deaths
Standardization is usually done for age > sex in order to compare death rates between the countries
Crude death rates are estimated by SRS in India. NFHS have also given data.
Only deaths from death certificate data are not the only source.