Which of the following is a characteristic of amphibians but not reptiles? a. amniotic egg b. backbone c. larval stage d. rough, dry skin

C

Explanation:

The amphibian larva represents a morphologically distinct stage between the embryo and adult. The larva is a free-living embryo. ... Not long after emerging from their egg capsules, larval salamanders, which have four fully developed limbs, start to feed on small aquatic invertebrates.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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