Ontario Building Code Practice Exam

Retaining walls serve the purpose of holding back soil and preventing erosion. Building a retaining wall taller than 1.5 meters would require a professional engineer's stamp to ensure the structure is designed and built safely. Choosing options A, C, or D would result in a retaining wall that exceeds the maximum allowable height without a professional engineer's stamp. This could lead to potential safety hazards and structural failures. Therefore, option B is the correct answer for a retaining wall that does not require a professional engineer's stamp.