Final answer:
The symptoms described are most indicative of Abruptio placentae, which can cause abdominal pain, a rigid abdomen, and heavy, bright red bleeding due to premature separation of the placenta from the uterus.
Step-by-step explanation:
The client's symptoms of stabbing abdominal pain, rigid abdomen, and heavy, bright red bleeding suggest that these findings are indicative of c) Abruptio placentae. Placenta previa typically presents with painless vaginal bleeding, which is distinctly different from the symptoms described. While ectopic pregnancy can cause abdominal pain and bleeding, the presentation would not typically include a rigid abdomen, which suggests a more acute and severe intra-abdominal process. A hydatidiform mole does not generally cause a rigid abdomen and is associated with excessive trophoblastic growth, which leads to different clinical signs.
Therefore, Abruptio placentae, the premature separation of the placenta from the uterus, is likely the correct answer based on the presenting symptoms. This condition is commonly associated with abdominal pain, rigidity due to potential blood collecting within the abdomen, and heavy vaginal bleeding. Immediate medical attention is required for this obstetric emergency.