The question asks what perithecium looks like as a fruiting body. Before checking the options, remember that ascocarps (fruiting bodies of the sac fungi) come in three broad shapes: a fully closed one, a flask shaped one, and an open cup shaped one, and the shape tells you how the spores get out.
- Unopened globose fruiting body: A rounded structure with no opening at all describes a cleistothecium, not a perithecium. Since perithecium does have an opening, this option is wrong.
- Flask shaped fruiting body without opening: This gets the shape right but denies the one feature that makes a perithecium useful, its pore. A flask with no way out would trap every spore inside, so this cannot be the answer.
- Flask shaped fruiting body with apical opening: This matches a perithecium exactly. It is pear or flask shaped, and it carries a narrow pore at the top called the ostiole, through which the asci release their spores.
- Cup shaped fruiting body: A cup shape describes an apothecium, where the whole upper surface stays open and exposed. That is a different ascocarp altogether.
The only description that fits both the shape and the presence of an apical pore is option (3), so a perithecium is a flask shaped fruiting body with an apical opening.
Let's summarize:
- Cleistothecium: fully closed, no pore.
- Perithecium: flask shaped, opens through an apical ostiole.
- Apothecium: cup shaped, open on top.
So the correct choice is the flask shaped fruiting body with an apical opening.