Answer the following question: Fact 1: Amphibians are the first true tetrapods, or vertebrates with four limbs. Fact 2: Ancathostega is one of the earliest tetrapods found, and by far the most complete. Given the two facts above, what do ancathostega have four of?

Choices:
[1]. Eggs.
[2]. feet.
[3]. Wings.
[4]. alveoli.
[5]. Lungs.
[6]. ovaries.
[7]. rings.
[8]. Limbs.
Answer:
[8].