Which organ of a flowering plant protects the seed? What types of this organ are distinguished?

Which organ of a flowering plant protects the seed? What types of this organ are distinguished? What other functions, besides protective, does it perform?

1) the fetus;
2) fruits are classified by consistency (juicy, dry opening and dry non-opening ones), by the number of seeds (single-seeded, two-seeded, multi-seeded), by origin (true, false, simple, complex, compound fruits);
3) the fruit serves for the formation, protection and distribution of the seeds contained in it.

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