A perfect square trinomial has a general structure which is
[tex]a^2\pm2ab+b^2[/tex]The one that meets this structure is
[tex]x^2+14x+49[/tex]We know it because it can be re written as
[tex]x^2+2\cdot7\cdot x+7^2[/tex]Which shows in a more explicit way the estructure of a perfect square trinomial. The right answer is c