The nth term if an AP is 5n + 2, then the sum of first n terms of the AP will be __________

• A. ( frac {n^2 8}{2} )
• B. ( frac {n^2 + 8}{2} )
• C. ( frac {n^2 9}{2} )
• D. ( frac {n^2 + 9}{2} )