Final answer:
Arnett considers 'emerging adulthood,' which spans from 18 to the mid-20s, to be an age of instability, where individuals experience life transitions and exploration in work and love.
Step-by-step explanation:
Arnett considers emerging adulthood to be an age of instability. This is option C in your multi-choice question. This period relates to individuals who are approximately between the ages of 18 to their mid-20s. It's characterized by significant life transitions and identity exploration, particularly around work and love. The factors contributing to this stage of development include longevity increases, changes in the workforce requiring higher education for career entry, and shifting cultural expectations that encourage young adults to explore various options before settling down, leading to delayed milestones such as marriage, career, and financial independence.