The trait that would be least useful in a phylogenetic analysis would be one that a) is detectable only in observations of early development. b) involves genetically inherited behaviors. c) is altered easily by small changes in diet. d) can be studied only in museum specimens. e) is heritable but is determined by many genes.

A trait that is altered easily by small changes in diet.

Explanation:

The phylogenetic tree explains the evolutionary relationship between the organisms. The phylogeny of the organisms will depend on the difference and similarities in their genetic or physical characters.

The traits that are used in phylogeny must be constant and present in the ancestors or in atleast a group. The trait that can be easily modified or changed cannot be used for the study of the evolutionary relationship. Hence, trait which is altered by diet cannot be used in phylogenetic analysis.

Thus, the correct answer is option (C).

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