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
Western blot technique is done for- 
Select and explain. 
A. Mitochondiral RNA, B. Double strand DNA, C. r-RNA, D. Protein
D: Protein
Answer: D: Protein 
Explanation: Visualization of a specific DNA or RNA fragment among the many thousand of contaminating molecules requires the convergence of a number of techniques collectively termed the blot transfer.

Southern blot → Detects DNA
Northern blot → Detects RNA
Western blot → Detects proteins (proteins are separated by electrophoresis, renatured and analysed for an interaction by hybridization with a specific labelled DNA probe).