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: Biochemistry
Which of following techniques analyzing for detection of variations in DNA sequence and Gene expression - 
Select and explain. 
A. Northern Blot, B. Southern Blot, C. Western Blot, D. Microarray
D: Microarray
Answer: D: Microarray 
Explanation: DNA microarray (DNA-chips) is used for detection or screening of variations in DNA sequences and gene expression analyzing thousands of gene at the same time.