C. glutaraldehyde
Glutaraldehyde is known to be effective against bacterial spores and is commonly used in medical and laboratory settings for sterilization. Ethanol and phenol can have some antimicrobial activity, but they are not as effective against spores as glutaraldehyde. Soap is primarily effective for cleaning and removing dirt and microbes but does not have the same level of disinfectant efficacy against spores.