What does the presence of a vestigial structure in a modern organism indicate?

a
Natural selection prepares the body of organisms so that, in the future, the vestigial structures may be used.
b
The vestigial structure was not used by the modern organism, so it became nonfunctional within the organism's lifetime.
c
A limited number of genes are expressed during the lifetime of an organism.
d
The structure was probably functional in some ancestor of the modern organism.

The answer is D, The structure was probably functional in some ancestor of the modern organism. Vestigial structures are structures that have remained from ancestors but have no function in modern times.

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hey bro i looked it up on google the structure of the eye-spot in euglena viridie, e. ehrenbergii, and phacus pyriyorme is not as franzé haa described it. the so-called “crystal body” and “lens bodies” were not found in any of the individuals of the species examined by me. as earlier observers have stated, the eye-spot consists simply of a mass of pigment granules arranged in a single layer, and probably embedded in a protoplasmic framework, but the latter could not be seen, and its presence was only inferred from the fact that the pigment granules must be held together in some way, thd the eye-spot as a whole is capable of expansion, and that the pigment granules can be separated from each other.

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