AMC 12B 2020 Problem 14

Bela and Jenn play the following game on the closed interval [0, n] of the real number line, where n is a fixed integer greater than 4 . They take turns playing, with Bela going first. At his first turn, Bela chooses any real number in the interval [0, n]. Thereafter, the player whose turn it is chooses a real number that is more than one unit away from all numbers previously chosen by either player. A player unable to choose such a number loses. Using optimal strategy, which player will win the game?

Answer Choices
A. Bela will always win.
B. Jenn will always win.
C. Bela will win if and only if n is odd.
D. Jenn will win
E. Jenn will win if and only if n>8.