Which statement is true about a scientific theory? Theories are based entirely on logic, and creativity plays no role in their development.
Theories cannot be discarded because they are based on sound science.
Theories are set in stone and cannot be changed.
Theories can be revised as new knowledge expands our understanding.

Theories can be revised as new knowledge expands our understanding.

Explanation:

A scientific theory is based on observations and logic that provide a valid answer to the question related to the world.

Scientific theories can be revised and change over time when a person encounters with new knowledge and helps to expand our understanding. Changes in scientific theories are the result of new scienctific observations and deep investigation about the context. The old theory can be revised as  a new theory become dominant over old and gives a new perspective to people.

Hence, the correct answer is "Theories can be revised as new knowledge expands our understanding."

the dark variety, as they are not visible on the dark tree barks

explanation:

the supermassive black hole is in the middle of the galaxy.