The type of hormonal interaction that occurs when more than one hormone acting on a target cell produce an amplified effect is

Synergism

Explanation:

Synergism occurs in the body when there is the combination of two or more hormones acting to produce effects which is more than the sum of their normal individual effect. For example the combination of follicle and testosterone hormones helps in stimulation for the usual production of sperm, if one of them is absent it could lead to either low or no sperm production at all, whereas if the two are present a man can produce about 300,000 sperm per minute.