To solve this problem, we need to determine which quantities have the same dimensions as a solid angle.$\\$A solid angle is a dimensionless quantity. It is defined as the ratio of the area of a portion of a sphere to the square of the radius of the sphere.$\\$The dimensional formula for a solid angle is $[M^0L^0T^0]. \\$Let's analyze the options:$\\$• Strain:$\\$Strain is the ratio of change in length to the original length. It is a dimensionless quantity.$\\$Therefore, the dimensional formula for strain is $[M^0L^0T^0]. \\$• Arc:$\\$Arc is a length and has dimensions $[L]. \\$• Angular speed:$\\$Angular speed is the rate of change of angular displacement with time. Its dimensions are $[T^{-1}]. \\$• Stress:$\\$Stress is defined as force per unit area. Its dimensions are $[ML^{-1}T^{-2}]. \\$• Angle:$\\$Angle is the ratio of arc length to radius, which is dimensionless.$\\$Therefore, the dimensional formula for angle is $[M^0L^0T^0]. \\$From the analysis, the quantities that have the same dimensions as a solid angle are strain and angle.$\\$Therefore, the correct option is Option 3: Strain and angle.