What is the most likely diagnosis for a patient presenting with frequent heartburn, mid-sternal/epigastric chest pain worsened by lying down and acidic food intake, along with risk factors such as obesity and hiatal hernia?
A) Gastroesophageal Reflux Disease (GERD)
B) Peptic Ulcer Disease (PUD)
C) Esophageal Cancer
D) Gastritis