**Core Concept**
The regulation of glycolysis involves a complex interplay of multiple enzymes, including those that activate or inhibit the pathway. AMP-activated protein kinase (AMPK) plays a crucial role in sensing energy status and activating key enzymes involved in glycolysis to restore ATP levels.

**Why the Correct Answer is Right**
AMPK is a key regulator of glycolysis, particularly in conditions of low energy, such as exercise or ischemia. When ATP levels decrease, AMPK is activated, leading to the phosphorylation and activation of key enzymes involved in glycolysis, including phosphofructokinase-2 (PFK-2) and hexokinase II. This activation of glycolytic enzymes increases glucose uptake and metabolism, ultimately restoring ATP levels. The activation of AMPK is mediated through its upstream kinase, LKB1.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as there is no clear link between this enzyme and the activation of glycolysis.
* **Option B:** This option is incorrect as it is actually an inhibitor of glycolysis, rather than an activator.
* **Option C:** This option is incorrect as it is not directly involved in the regulation of glycolysis.

**Clinical Pearl / High-Yield Fact**
AMPK is often referred to as the "energy sensor" of the cell, as it plays a crucial role in regulating energy metabolism in response to changes in ATP levels.

**Correct Answer:** C. AMPK. AMP-activated protein kinase.