**Core Concept**
Spermicides are a type of non-hormonal contraceptive that work by disrupting the process of fertilization. They are typically used in combination with other barrier methods, such as condoms, to prevent pregnancy. The primary mechanism of action of spermicides is to create an environment that is unfavorable for sperm to fertilize an egg.

**Why the Correct Answer is Right**
Spermicides typically contain a chemical called nonoxynol-9, which works by releasing acrosomal enzymes from the sperm. These enzymes are essential for the sperm to penetrate the outer layer of the egg (zona pellucida) and fertilize it. By releasing these enzymes, spermicides prevent the sperm from reaching the egg, thereby preventing fertilization. This mechanism is specific to sperm and does not affect the egg or other cells in the body.

**Why Each Wrong Option is Incorrect**
**Option B:** Lysis of cell membrane is a mechanism of action for certain types of antimicrobial agents, such as antibiotics and antifungals, but it is not how spermicides work.

**Option C:** Glucose uptake inhibition is a mechanism of action for certain types of antidiabetic medications, such as metformin, but it is not related to the mechanism of spermicides.

**Option D:** Vaginal enzyme alteration is not a known mechanism of action for spermicides. While enzymes play a crucial role in many biological processes, spermicides work by releasing acrosomal enzymes from the sperm, not by altering vaginal enzymes.

**Clinical Pearl / High-Yield Fact**
It's essential to note that spermicides should be used in combination with other barrier methods to prevent pregnancy. Additionally, spermicides may not be effective in preventing STIs, as they do not provide a physical barrier against the transmission of pathogens.

**✓ Correct Answer: A. Release of acrosomal enzymes**