Which choice correctly positions the subject in relation to the modifying phrase?

The choice that correctly positions the subject in relation to the modifying phrase is "Tom was given a chance." This structure clearly presents Tom as the subject who receives the action of being given a chance, allowing the modifying phrase "a chance" to directly relate to him.

In this construction, the passive voice is employed, emphasizing Tom's experience rather than the teacher's action. This positioning effectively centers the subject of the sentence—Tom—while also providing clarity about what he receives.

Option "A" fails to include any additional context about a chance being given, making it incomplete. "C" also does not adequately specify the recipient of the action or the modifying phrase. "D" stands alone as a fragment and does not present a complete thought or any subject-verb relationship. Thus, the selected choice is the only one that effectively integrates the modifying phrase and identifies the subject clearly.