Final answer:
Among the given options, Alexandra, the 30-year-old pregnant female, would not be covered by Medicare, as it primarily insures individuals 65 and older, younger individuals with certain disabilities, and those with ESRD or ALS.
Step-by-step explanation:
The patient who would not be covered by Medicare among the options provided is Alexandra, a 30-year-old female who is pregnant. Medicare is a government program that provides health insurance primarily to individuals who are 65 years and older, as well as younger individuals with disabilities and those with end-stage renal disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS).
DJ, the 75-year-old male with heart disease, would be covered because of his age. Justin, the 20-year-old male with a spinal cord injury, is eligible through Social Security Disability Insurance benefits. Daniel, the 50-year-old with ESRD, is eligible due to his specific medical condition.