Only certain organs called the target organs respond to the presence of a specific hormone because

Because receptors which are sensitive to the specific hormones are present only in the target organs

Explanation:

Hormones receptors are specialized proteins which are sensitive to particular hormone stimulus. They are responsible for receiving hormones signals as inputs in the target organs, to produce cascade of events as response in the target organs. They usually need small concentration of specific hormones to bind with to produce large effects in corresponding cells functions and morphology.

They can be located in cell membrane where they are called peptide hormone receptors; thus they receive input signals from peptide hormones from the cells surfaces, and stimulated cascade of events to bring about responses inside the cells. Therefore are also called trans-membrane receptors.

However, some can be integrated within the cytoplasm, where they are called nuclear receptors. to initiate cascade of events in the cells which affect the functions of the cells either for secretion or intake of a particular substances.