The correct option is
C Nourish their young ones with milk
Not all mammals possess a uterus. Some mammals that posses uterus are dogs, dolphins, whales, elephants and all primates.
Some mammals like platypus and echidna are egg-laying mammals and do not give birth to live young.
All mammals have mammary glands and nourish their young ones with milk.
Young ones have fine hair or fur on their skins and no thick coats.
So the correct answer is 'Nourish their young ones with milk'.