Distinguishing Characteristics of Gram-positive Bacteria

In microbiology, the classification of bacteria is often based on their shape and other characteristics. One of the most commonly used methods for classifying bacteria is the Gram stain, which differentiates bacteria into two groups based on their cell wall composition. Gram-positive bacteria retain the crystal violet stain and appear purple, while Gram-negative bacteria do not retain the stain and appear pink after being counterstained.

Which of the following is a characteristic that specifically distinguishes Gram-positive bacteria from Gram-negative bacteria?