Final answer:
Leptin is a hormone produced by adipose tissue that reduces hunger by signaling to the brain that the body has enough energy stored, which is critical for energy balance and reproductive functions. the correct answer is D.
Step-by-step explanation:
Leptin is a hormone produced by fat (adipose) tissue that suppresses hunger by signaling satiety to the brain. In essence, it has a key role in the long-term regulation of energy balance, affecting both food intake and energy expenditure based upon the body's fat stores. Levels of leptin increase with higher fat stores, leading to reduced appetite, whereas lower fat levels result in decreased leptin and increased hunger.
It is also fundamental for reproductive functions as it affects the synthesis of gonadotropins and onset of puberty. Leptin resistance, associated with obesity, manifests as a decreased sensitivity to leptin, contributing to difficulties in achieving satiety and a propensity for overeating, worsening the condition. Higher fat stores result in more leptin and reduced appetite. Leptin resistance can lead to obesity, as it causes an inability to feel satiated.