Hemoglobin and gold sol are examples of

The concept used: Surface Chemistry

Detailed explanation: Hemoglobin and gold sol are examples of positively and negatively charged. A colloid is a combination in which one component is suspended in another by microscopically distributed insoluble particles. Some definitions, however, stipulate that the particles must be dispersed in a liquid, while others broaden the concept to include aerosols and gels. A high number of atoms or smaller molecules of a material cluster together during dissolution to produce colloidal species (less than 1 nm). Multimolecular colloids are the result of this process. For example, gold sol and sulfur sol.

Hence, the correct answer is option A) positively and negatively charged.