Final answer:
The theme of the dangers of secrecy is most prominently developed through Victor's creation and pursuit of the monster in 'Frankenstein', highlighting the fatal consequences of isolating one's work from ethical scrutiny and the community.
Step-by-step explanation:
The incident from Frankenstein that most clearly develops a theme related to the dangers of keeping one's intentions secret is D. Victor's creation and pursuit of the monster. This core narrative event encapsulates the story's warning against unchecked scientific ambition and the peril of isolated endeavors without communal scrutiny or ethical consideration. Victor Frankenstein's secretive work on reanimation culminates in a creature whose existence becomes a burden to himself and a terror to others. The repercussions of Victor's covert operations and the refusal to disclose his secret, even when Justine's life is at stake or when the monster begs for understanding, result in multiple tragedies, including the death of his loved ones and ultimately his own destruction.
By refusing to share his scientific pursuits with his peers or family, Victor's ambition turns into a fatal flaw, leading to devastating consequences that echo themes from gothic tales and Frankenstein's Romantic context. The text prompts readers to question not just the pursuit of knowledge, but also the moral responsibilities that come with creation.