Final answer:
The correct term for the case that protects shark eggs is a 'shark egg case' or 'mermaid's purse', and among the given options, it is referred to as a 4. 'capsule'.
Step-by-step explanation:
Shark Egg Cases
The case that protects shark eggs is known as a "mermaid's purse" or a shark egg case. Among the given options, the correct term would be a 4. capsule.
Shark embryos are housed within these protective cases, which often feature tentacles or fibers that anchor them in seaweed, providing cover for the developing shark. Not to be confused with an ootheca, which is an egg case for insects and certain mollusks, or a placenta, which is a structure providing nourishment to embryos in viviparous creatures, including mammals and some sharks.
The correct answer to the student's question is Option 4: Capsule.