Final answer:
The correct answer for the inability to roll or curl the tongue, a recessive trait, is 'C. hh', where 'h' represents the recessive allele for the trait. Options 'HH' and 'Hh' would show the dominant trait, while 'D. H' is incomplete.
Step-by-step explanation:
When discussing autosomal dominant and recessive traits, the ability to roll or curl the tongue is a dominant trait. As such, having the recessive phenotype, which is the inability to perform this action, would be represented by two copies of the recessive allele. In genetic terms, this is denoted by 'hh'.
Given the options provided by the student, the answer representing the lack of the ability to roll the tongue would be 'C. hh', as this indicates that the individual has inherited the recessive allele from both parents, thus expressing the recessive trait. Individuals with 'HH' or 'Hh' genotype would be able to roll their tongue, while 'hh' denotes the lack of this ability. The option 'D. H' is not a complete representation of genotype as it only shows one allele.