Answer:3rd option: 60 degrees Step-by-step explanation:We can see in the diagram that the angle on C is a supplementary angle, which means that the sum of 135 and internal angle will be equal to 180 degrees. Let x be the internal angle,Thenx+135 = 180x = 180-135x = 45 degreesSo now we know that two interior angles of the triangle.Also we know that sum of all internal angles of triangle is 180 degrees.Using the same postulate:A+B+C = 18075 + B + 45 = 180120+B = 180B = 180 - 120B = 60 degreesSo,third option is the correct answer ..