The Mendelian trait are those controlled at only single gene locus. The Mendelian trait have two alleles (one form each parent), out of which one allele is dominant while the other is recessive. The dominant allele will express in both homozygous and heterozygous conditions while the recessive allele will express itself only in homozygous condition. An example of the human Mendelian trait is the attached or detached earlobes. A human will either have attached earlobe or detached earlobe.
Hence, the correct answer is 'Option C - humans either have attached earlobes or detached earlobes'.
