Which of these is not an advantage of using a stratified sample

Which of these is not an advantage of using a stratified sample instead of a simple random sample?
A) the stratified sample eliminates the need for randomization
B) the stratified random sample allows you to get information about each stratum
C) the stratified sample allows you to get more reliable estimates using the same sample size
D) the stratified sample reduces sample to sample variability
E) the stratified sample reduces bias
Answer: E

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