Do sharks lay eggs or give birth?

Sharks are slow growing, late maturing and have a low reproductive rate.
Most sharks give birth to live young instead of laying eggs.

Sharks that give birth to live babies (called pups) usually only have very few at one time. For example, a great white shark only has four to 10 pups. Some sharks are pregnant for two to three years before giving birth

ref :http://www.marinediscoverycentre.com.au/Downloads/Sharks.pdf