The tagline that the greeting card company should use to invoke affection is "Show that you care."
This tagline is focused on expressing affection and indicating that the person cares for the recipient, which is directly related to the company's goal of designing an advertisement that invokes affection.
On the other hand, the other options, such as "Win the race," "Take pride in your achievement," and "Grab an opportunity," are more focused on achievement and competition, which are not directly related to the goal of invoking affection.