This is the relevant information: In his poem, "The Charge of the Light Brigade" (1854), Tennyson famously dubbed this hollow "The Valley of Death".
This justifies what answer for what question? Q & A:
Passage: In response to the order, Lucan instructed Cardigan to lead his command of about 670 troopers of the Light Brigade straight into the valley between the Fedyukhin Heights and the Causeway Heights. In his poem, "The Charge of the Light Brigade" (1854), Tennyson famously dubbed this hollow "The Valley of Death".

Question: Based on this passage, where did charge of the light brigade take place?
the valley between the Fedyukhin Heights and the Causeway Heights