What is indicated by the term "distend"?

The term "distend" refers specifically to the action of swelling or stretching. This is often used in medical or physiological contexts to describe the way certain body parts may enlarge or expand, often due to the accumulation of fluid or gas. Such a reaction can occur in various biological systems, where pressure increases internally, causing the tissue to become larger than normal. This definition aligns precisely with the meaning of the term, making it the correct choice.

In contrast, the other options represent different actions: breaking apart into pieces implies fragmentation, decreasing in size indicates contraction, and making known a secret pertains to revelation or disclosure. These definitions do not align with the meaning of "distend" and illustrate distinct concepts rather than the process of swelling or stretching.