Answer: The term that best describes the U-shape tongue trait in this context is dominant.
Explanation: In genetics, traits are determined by alleles, which are different versions of a gene. Alleles can be dominant or recessive. If an individual only needs one copy of the allele to express the trait, it is a dominant allele. In this case, the ability to curl the tongue into a U-shape is determined by an allele that is dominant, meaning if the allele is present, the trait will be expressed, regardless of the presence of other alleles.