What is a nebula?

the core of a massive star
a cloud of gas and dust in space
a swirling disk with a lot of gravity
the debris remaining after a supernova

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen

The galapagos island contain 13 species of finches four of the species are seen here it is believed that all of the species had one common ancestor and overtime

The picture represents a structure of the respiratory system. which is the function of this structure? to bring air into the body to exchange oxygen with carbon dioxide to carry air to the lungs to release oxygen from the body