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
Epigenetics is ? 
Select and explain. 
A. Alteration in nucleotide sequence, B. Alteration in chromosome number, C. Alteration in gene expression, D. Alteration in chromosome size
C: Alteration in gene expression
Answer: C: Alteration in gene expression 
Explanation: Ans. is 'c' i.e., Alteration in gene expression Epigenetics is a heritable change in the level of gene expression, not caused by changes in DNA sequence. It includes changes like Histone modification or DNA methylation