Complex organisms with gills and lungs were major life forms that existed in

a.

mesozoic era

c.

precambrian era

b.

cenozoic era

d.

paleozoic era

D-Paleozoic era.

Complex organisms with gills and lungs were major life forms that existed in the Paleozoic era.

The earliest and the longest of the the Phanerozoic era is the Paleozoic era. The Paleozoic era is divided into 6 geologic periods namely the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

the correct ansewr is D)  paleozoic era

amber has allowed scientists to study dna that has been preserved over millions of years.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.