How can pregnancy be diagnosed?

Pregnancy can be diagnosed effectively through the measurement of human chorionic gonadotropin (hCG) levels in the body. This hormone is produced shortly after a fertilized egg attaches to the lining of the uterus, and its presence in the bloodstream or urine is a strong indicator of pregnancy. Tests that measure hCG levels are typically very sensitive and can provide confirmation of pregnancy as early as a week after conception.

While abdominal ultrasound is a valuable tool for visualizing the fetus and assessing the pregnancy's development, it is not typically used as a primary method for initial pregnancy diagnosis. A physical examination might provide some indicators of pregnancy, such as changes in the cervix or uterus, but these are less definitive than hCG testing. Similarly, urine pH testing does not play a role in diagnosing pregnancy, as it is not indicative of hormonal changes associated with pregnancy.

Thus, raised hCG levels are the most reliable and widely accepted method for confirming pregnancy, making this response the correct choice.