**Core Concept:** Glutaraldehyde is a widely used fixative and disinfectant in medical and scientific settings. It is a strong aldehyde that interacts with biomolecules, primarily proteins, to cause cross-linking and precipitation, leading to tissue preservation and sterilization.

**Why the Correct Answer is Right:** Glutaraldehyde is typically used in concentrations ranging from 2% to 8%. The correct answer, **2%, is the minimum concentration required for significant fixation and sterilization.** Lower concentrations might not be effective in preserving tissue structure and killing microorganisms effectively.

**Why Each Wrong Option is Incorrect:**

A. **1%:** A concentration of 1% glutaraldehyde is too low to provide adequate tissue preservation and sterilization.

B. **5%:** Glutaraldehyde, when used at such high concentrations, can cause tissue damage and tissue shrinkage, making it unsuitable for medical applications.

C. **7%:** Although higher than the correct answer, 7% glutaraldehyde is still higher than the optimal range for tissue preservation and sterilization, leading to excessive tissue damage and reduced efficacy.

**Clinical Pearl:** Glutaraldehyde is a versatile agent, but its use should be tailored to the specific application, considering factors like tissue preservation, sterilization, and potential side effects. In medical settings, 2% glutaraldehyde is a commonly used concentration for various purposes, ensuring effectiveness without causing excessive damage.