∆PQR was rotated and then dilated by a scale factor of 9 to create ∆P''Q''R''. Which statement explains why ∆PQR is similar to ∆P''Q''R''?

Rotations and dilations preserve collinearity; therefore, the corresponding angles of ∆PQR and ∆P''Q''R'' are congruent.
Rotations and dilations preserve orientation; therefore, the corresponding angles of ∆PQR and ∆P''Q''R'' are proportional.
Rotations and dilations preserve angle measure; therefore, the corresponding angles of ∆PQR and ∆P''Q''R'' are congruent.
Rotations and dilations preserve side length; therefore, the corresponding sides of ∆PQR and ∆P''Q''R'' are congruent.