B$.$ Ali is deciding whether or not get a double major. That decision is denoted by binary decision variable D$1,$ where $1$ means going for a double major and $0$ means otherwise. If they go for it$,$ they must collect $10$ points. They would collect n points for taking any Xn for advance classes, i$.$e$.,$ n $=4,5,6.($In other words, they'd collect $4$ points for taking X$4,5$ for taking X$5,$ and $6$ for taking X$6.)$

$*$X$4+$

$*$X$5+$

$*$X$6>=$ D$1$