Answer the following question given this paragraph: 

Vertebrates reproduce sexually, and almost all of them have separate male and female sexes. Generally, aquatic species have external fertilization, whereas terrestrial species have internal fertilization. Can you think of a reason why aquatic and terrestrial vertebrates differ in this way?.


Q: In which way do vertebrates reproduce?

 Choices:

- bisexually

- unisexually

- asexually

- sexually

A:
sexually
