A characteristic that can possibly be shared by both living and non-living organisms is:

Question 39:
A characteristic that can possibly be shared by both living and non-living organisms is:

• A. Locomotion: While some non-living things can move, true locomotion (self-propelled movement) is a characteristic of living organisms.
• B. Irritability: This is the ability to respond to stimuli, which is a defining characteristic of living organisms.
• C. Increase in biomass: Biomass refers to the mass of living matter. Non-living things do not increase in biomass.
• D. Increase in size: Both living organisms (through growth) and non-living things (e.g., crystals, sand dunes through accretion) can increase in size.

The correct option is D.

The final answer is $\boxed{\text{D. increase in size}}$.