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: Dental
The ideal data for stratified sampling: 
Select and explain. 
A. Heterogenous data, B. Homogenous data, C. Both, D. None
A: Heterogenous data
Answer: A: Heterogenous data 
Explanation: Stratified Random Sampling

The non-homogenous population is converted to homogenous groups/classes (strata); sample is drawn from each strata at random, in proportion to its size.
Applicable for large non-homogeneous population.
Gives a more representative sample than simple random sampling.
None of the categories is under or over-represented.
For example, In a population of 1000, a sample of 100 is to be drawn for Hemoglobin estimation; first convert non-homogenous population to homogenous strata (i.e. 700 males and 300 females), then draw 70 males and 30 females randomly respectively.