Final answer:
The term for the relatively constant internal physical environment of an organism is homeostasis, which is crucial for an organism's proper functioning, including cellular activities, growth, and reproduction.
So, the correct answer is B.
Step-by-step explanation:
The term that describes the relatively constant internal physical environment of an organism is homeostasis. This biological concept is integral to an organism's ability to function properly. Maintaining homeostasis means that despite changes in the external environment, organisms need to regulate their internal conditions to remain stable and viable. This regulation involves multiple systems within an organism that work continuously to maintain optimal conditions for cellular processes, growth, and reproduction. As such, dynamic homeostasis is essential for life and involves complex interactions between various biological systems.
So, the correct answer is B.