Which of the following is an oviparous mammal that produces milk but lacks nipples?

Ornithorhynchus (Platypus) is oviparous. Like all other mammals, monotreme mothers produce milk for their young. But unlike other mammals, monotremes like the platypus lack nipples. Their milk oozes out of mammary gland ducts and collects in grooves on their skin, where the nursing babies lap it up or suck it from tufts of fur.

Pteropus, Macropus and Balaenoptera have mammary glands with nipples.