Final answer:
The correct examples of vestigial structures are snake limbs and horse toes, as well as hind leg bones in whales and leaves on some cacti, as they are remnants of their evolutionary past with no current function.
Step-by-step explanation:
Vestigial structures are physical features in organisms that have no apparent function and are considered remnants of evolutionary ancestors. Examples of such structures include the wings of flightless birds or the tiny remnant of a once-larger appendix in humans. Answering the question, option c) Snake limbs and horse toes would be correct as snakes have pelvic bones despite having no legs, descending from reptiles that did have legs, and horses have remnants of additional toes which are no longer used. Both structures are not necessary for the current lifestyle or survival of these species and are indications of their evolutionary past. Option c) hind leg bones in whales and leaves on some cacti is also correct since hind leg bones in whales are remnants of their ancestors that had fully developed legs, and cacti still have leaves despite having evolved to use spines for necessary functions such as reducing water loss and sunburn protection, which indicates a vestigial trait from ancestors that had larger leaves.