Final answer:
The two species of ungulates that do not shed their horns are the D. pronghorn and bighorn sheep.
Step-by-step explanation:
The ungulates, or hoofed animals, include various species that are distinguished by having either horns or antlers. The two species of ungulates that do not shed their horns are the pronghorn and bighorn sheep.
This means the correct answer is D. Pronghorn and bighorn sheep.
Most other ungulate species like moose, caribou, elk, mule deer, white-tailed deer, and reindeer shed their antlers annually, whereas pronghorns have branched horns that they retain for life, and bighorn sheep have unbranched horns that also grow throughout their lives.