Respuesta :

Answer: both 1 and 2

Explanation: common sense

Both 1 and 2 are a characteristic of all mammals.

What are the characteristics of mammals?

Characteristics of Mammals are:

  • The presence of hair or fur.
  • Sweat glands.
  • Glands are specialized to produce milk, known as mammary glands.
  • Three middle ear bones.
  • Specialized teeth.
  • A four-chambered heart

Thus,  Both 1 and 2 are a characteristic of all mammals.

To learn more about Mammals click here:

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