A couple in their mid-30s are at their primary care provider's office because they have been unable to conceive for 3 years. They already have one child who is 4 years of age. The care provider explains to them that they are dealing with what kind of infertility?
secondary infertility

There are two main types of infertility: primary and secondary. A couple who has never been able to conceive has primary infertility, whereas a couple who has been able to conceive in the past but is currently unable to do so has secondary infertility. T/F

TRUE

Explanation:

There are two types of infertility.

Primary infertility

Secondary infertility

In primary, couple have never conceived whereas secondary infertility refer to those couple who have been pregnant in the past at least once but now are unable to conceive

it would be c. xylem.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.