Step 1: Recall the setting.
By 1858, the main centres of the 1857 revolt had fallen, but Rani Lakshmibai of Jhansi continued to resist the British forces.
Step 2: Identify her ally.
After losing Jhansi, she moved toward Gwalior and joined forces with Tatya Tope, a trusted commander of Nana Sahib and one of the ablest rebel generals of the revolt.
Step 3: What they did together.
With Tatya Tope's cooperation, Rani Lakshmibai helped capture the Gwalior fort from the forces loyal to the Scindia ruler, who supported the British.
Step 4: The final answer.
The correct answer is Tatya Tope. Rani Lakshmibai was killed soon after in battle near Gwalior in June 1858, but her stand alongside Tatya Tope became one of the most remembered episodes of the revolt.