Which substance is primarily used as a stimulant in beverages like coffee?

Caffeine is the primary stimulant found in beverages such as coffee. It works by blocking the action of adenosine, a brain chemical involved in sleep, thereby increasing alertness and reducing the perception of fatigue. This leads to heightened energy levels and improved concentration, making it a widely used substance for enhancing cognitive performance and physical endurance.

In coffee, caffeine is present in varying concentrations, contributing to its stimulating effects that many people seek in their daily routines. This is well-supported by scientific literature, which consistently highlights caffeine's role in improving focus and exercise performance.

The other substances listed do not primarily serve as stimulants in common beverages. Dehydroepiandrosterone (DHEA) is a hormone that is involved in the production of other hormones but is not used for its stimulant effects in beverages. Tetra-hydro-gestrinone is a banned substance often associated with performance-enhancing drugs in sports, and gonadotrophin is a hormone related to reproductive functions. Therefore, caffeine stands out as the well-established stimulant present in coffee and similar beverages.