Assume you want to estimate$/$predict total viewership $($number of total views that day$)$ for every single TV network as a function of the amount of minutes each day they ran Political Ads, and you have data for every day for the past month for every firm.$$ If you include TV network fixed effects $($i$.$e$.$ a dummy for CNN$,$ a dummy for Fox, etc.$).$ Which of the following are you controlling for?$$

Group of answer choices

Network$-$invariant characteristics for each day

Time$-$variant characteristics for each Network

Time$-$invariant characteristics for each Network

Network$-$variance characteristics for each day

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