Which of the following describes all living things?

The choice stating that all living things grow and respond to stimuli is correct because these are fundamental aspects of life that characterize living organisms. Growth refers to a process where organisms increase in size and often in complexity, involving cellular division and differentiation. The ability to respond to stimuli encompasses how organisms react to changes in their environment, which is crucial for survival. This response can be seen in simple organisms as well as complex ones, and it plays a vital role in their adaptation and interaction with the world around them.

In contrast, the other options do not apply universally to all living organisms. While some living things are multicellular, not all are; for instance, bacteria and some types of algae are unicellular. The presence of a nucleus is also characteristic of eukaryotic cells, but prokaryotic organisms like bacteria lack nuclei. Lastly, while many plants and some microorganisms can carry out photosynthesis, not all living things have this capability; many organisms, such as animals and fungi, obtain energy through other means. Thus, the ability to grow and respond to stimuli is a defining feature that applies to all living organisms, making it the most accurate choice.