Will and Grace Have Adjoining Unfenced Back Yards and Each

Will and Grace have adjoining unfenced back yards and each has just adopted a new puppy.Will values a fence between their yards at $250 and Grace values a fence between their yards at $200.The value of the effort required to build the fence is $300,which will be split equally if they both help build the fence.If one of the neighbors begins building the fence the other might or might not come over to help.Therefore,their payoff matrix is $\begin{array}{c}\text { Will }\\\text { Grace } \begin{array}{|c|c|c|}\hline &\text { Build } &\text { Not Build } \\\hline \text { Build } & \text { Grace: } \$ 50 ; \text { Will: } \$ 100 & \text { Grace: } \$ 100 ; \text { Will: } \$ 250 \\\hline \text { Not Build } & \text { Grace: } \$ 200 \text {; Will: }-\$ 50 & \text { Grace: 0; Will: } 0 \\\hline\end{array}\end{array}$
If Grace sees Will building the fence she would earn a higher payoff by

A) helping him.
B) not helping him because she values the fence by less than does Will.
C) an uncertain amount.It depends on whether it is a sequential game or a simultaneous game.
D) not helping him because she will get the value of the fence without expending the effort.