Which of the following is the most likely diagnosis for Mrs. Santos based on the given information?

Mrs. Santos, a 32-year-old pregnant woman, presents to the antenatal clinic for her routine check-up at 32 weeks of gestation. She complains of painless vaginal bleeding. On examination and the fundus of the uterus is found to be at the level of the umbilicus. The fetal heart rate is within normal limits. The blood pressure is 130/80 Mmhg.