Infant characteristics can evoke the kindness and parenting of adults, and many animals have the characteristics and behaviours of human babies. Therefore, people are easily attracted to such animals and make them pets. Which of the following, if true, best supports the above conclusion? ['Many empty nest elderly like to keep pets.', 'Big and fierce animals rarely become pets.', 'Some families no longer have pets after having children.', 'Parents like pets, and children like pets.']