The correct answer is:
b. stress.
When an organism is faced with a demand to adapt to changes in its environment, this is referred to as "stress." Stress can be caused by various factors such as physical, emotional, or environmental challenges that require the organism to adjust in order to maintain its equilibrium or balance. For example, a plant experiencing drought stress may need to adapt by developing mechanisms to conserve water, while an animal facing a predator may need to respond with fight or flight reactions to survive. Stress can be a normal part of an organism's life cycle and can lead to growth and development when managed effectively.
