Kelly sells magazine subscriptions after work. The half-year subscriptions cost $12, and the full-year subscriptions cost $20. Today, Kelly has 20 subscription cards with her, only one subscription can be ordered on each card, and she wants to sell subscriptions totaling at least $300.
If the solution region represents the amount of half-year and full-year magazine subscriptions Kelly needs to sell to reach her goal, which graph's shaded area represents the solution region?