Ross was a Scottish philosopher who died in 1971. He is well-regarded in the academic institutions which makes it sensible that B and C encountered his seminal text. He attempted to make a sound ethical theory. That is, one that could assist in almost every ethical problem encountered.
The connection between law and morality is complex, and there may be no general rule that captures how the two are related.
Everyone is capable of committing unethical actions without even realizing what they are doing is unethical.
Eighteenth century philosopher David Hume famously argued that inferences in which what we ought morally to do are derived from non-moral states of affairs are logically flawed. You cannot, according to Hume, derive an “ought” from an “is,” at least without a supporting “ought” premise.
Virtually all non-psychopaths think murder is morally wrong. But what makes it so? Is the wrongness an objective fact, one that would exist no matter how people felt about it? Or does the wrongness of murder reside only in people’s minds, with no footing in objective reality?