Human height is one of the traits that belong to traits that cannot easily be placed in discrete phenotypic classes (there is not only tall and short people, there is continuous variation of height between them). Such traits are usually controlled by more than one gene (polygenic traits).
On the other hand, a Mendelian trait is controlled by a single locus.
This question is supposed to have a table showing species member tested and the type of cells tested and the results. Based on this table, the species member that would be unlikely to pass the gene mutation on to its offspring is species member 4: [Body cells (+) and Sperm (-)] Hope this helps.
