Natural Selection Question 3

In a species of cactus, the number of spines on a plant is genetically determined. The graph above shows frequency distributions for populations of the cactus species growing in the presence or absence of two herbivores: peccaries (a New World pig) and wasp larvae. Which of the following best accounts for the different frequency distributions in the graph?

Peccaries eat cacti with the greatest number of spines, and wasp larvae show no preference with respect to spine number.

Peccaries eat cacti with a smaller number of spines, and wasp larvae eat cacti with a greater number of spines.

Wasps have increasing difficulty depositing eggs on cacti with more spines, and peccaries show no preference with respect to spine number.

Both peccaries and wasp larvae will eat the most abundant types of cacti, which are the plants with the greatest number of spines.