Final answer:
When a true breeding short-haired cat is mated with a long-haired cat, all the kittens will exhibit the dominant phenotype of short hair, as long hair is recessive.
Step-by-step explanation:
In cats, the long hair gene is recessive, while short hair is dominant. When a true breeding short-haired cat (whose genotype is likely to be homozygous dominant for the short hair trait) is mated with a long-haired female (which is homozygous recessive), all offspring will inherit one short hair allele from the short-haired parent and one long hair allele from the long-haired parent. Consequently, each kitten will have the genotype for short hair (heterozygous), and as short hair is dominant, all of the kittens will phenotypically exhibit short hair.
Although coat color has a sex-linked inheritance pattern in cats, this genetics question is more concerned with coat length, not color. Thus, all kittens will show the dominant phenotype which is short hair, irrespective of their sex.