DSE 2017 Question 16: Game theory and strategic behaviour

In a two-player game, player $1$ first chooses $U$ or $D$. Playing $D$ ends the game with payoffs $(1,0)$. Playing $U$ lets player $2$ choose $U$ or $D$: player $2$'s $D$ ends it with $(0,2)$, while $U$ lets player $1$ choose again - player $1$'s $D$ gives $(4,0)$ and $U$ gives $(3,3)$ (payoffs are (player $1$, player $2$)). This game has