Answer:
C: it extends from the Ural mountains to the Yenisey River
Step-by-step explanation:
It is not b as Siberia is covered in swamps and marshes. It does not extend from the Lena river to the Pacific cost, so it is not A. There's not enough info on D for me to properly decide, as it just ends in "square" because Siberia does cover 2.6 to 2.7 million square kilometers. So from my view, the best answer is C.