Question

complete the following sentence.
_____ and ___ reproduce using external fertilization, whereas ___ and _____ reproduce using internal fertilization.

a fish, sharks, frogs, humans
b frogs, snakes, eels, bears
c fish, frogs, birds, humans
d fish, lizards, frogs, bears

Explanation:

To solve this, we analyze fertilization types:

• External fertilization: Occurs outside the body. Most fish (except sharks) and frogs use this.
• Internal fertilization: Occurs inside the body. Sharks, birds, humans, reptiles (snakes, lizards), and mammals (bears) use this.

Now check options:

• Option a: Fish (external), sharks (internal) – no, but wait, correction: Most fish (like bony fish) use external, sharks (cartilaginous) use internal. Frogs (external), humans (internal). Wait, no, the option is "fish, sharks, frogs, humans" – no, sharks use internal. Wait, no, re - evaluate:
• Option c: Fish (external, most), frogs (external), birds (internal), humans (internal). This fits: external (fish, frogs); internal (birds, humans).
• Option a: Sharks use internal, so "fish, sharks" – sharks are internal, so first part wrong.
• Option b: Snakes (internal), eels (some fish, external? But snakes are internal, so first part (frogs, snakes) – snakes are internal, so wrong.
• Option d: Lizards (internal), so first part (fish, lizards) – lizards internal, wrong.

So option c has external (fish, frogs) and internal (birds, humans).

Answer:

c. fish, frogs, birds, humans