Consider the following argument:

$$ Salt is required for every recipe in this cookbook. $$ My dad wants me to cook a meal for his $70$th birthday. $$ My dad's doctor has told him to cut salt out of his diet. $$ If I cook my dad a recipe from this cookbook, his doctor will be mad. So $$ I can't cook a recipe from this cookbook. After all, $$ I don't want my dad's doctor to be mad. $$ I need to get a new cookbook before my dad's $70$th birthday.

In a map of this argument, what is the role of $?$

It is an independent premise that supports $$

It is an independent premise that supports $$

It is a joint premise that, together with $$ and $,$ supports $$

It is a joint premise that, together with $,$ supports $$

It is the conclusion of the argument