Problem $4(5$ points$)$

Consider the three nodes Cavity, Catch, T oothAche that are being added to the belief network. Let$$s say Cavity and Catch

are already added and connected as shown below $($solid arrow$).$ Once T oothAche is added, which dashed arrow$($s$)$ need to

be connected? $(1$ or $2$ or both: mark below$)?$ Explain why. $($Hint: think in terms of cause and effect.$)$

Cavity Catch

ToothAche

$(2)(1)$