Who is calling me (voice change). ?

The question "Who is calling me?" implies an inquiry about the subject of an ongoing action, specifically, who is currently performing the action of calling. To transform this question into a more formal structure while retaining its meaning, we can analyze the provided options.

Option A, "By whom am I called?" and Option B, "By whom I am called?" both incorrectly suggest a completed action rather than an ongoing one. They imply a state of being called in the present, which does not reflect the immediate context of someone actively calling.

Option D, "whom I called by?" features incorrect syntax. The proper sentence order in English would require "By" to precede the subject.

Option C, "By whom am I being called?" is grammatically correct and captures the essence of the original question. It uses the passive voice to indicate that the action (calling) is currently happening to the speaker, thus effectively pinpointing the present participatory nature of the inquiry. The use of "being" signals that the action is ongoing, making this option the most accurate representation of the original question's intent.