Identical Twins Jada and Olivia Were Very Similar in Personality

Multiple Choice

Identical twins Jada and Olivia were very similar in personality throughout childhood. After high school, Jada majored in music and became an elementary school teacher, while Olivia earned a medical degree and joined Doctors Without Borders, traveling to countries gripped by war and epidemics. Later in life, Olivia was more prone to risk-taking than Jada. This difference in personality is a result of

A) niche-picking.
B) alterations to Olivia's chromosome-5 gene.
C) mutations in Olivia's DD genetic makeup.
D) methylation.