△DEF is reflected to form​​ ​ △D′E′F′ ​. The vertices of ​ ​ △DEF ​ ​ are ​ D(−1, −1) ​, ​ E(1, −1) , and ​ F(−1, −6) ​. The vertices of ​ △P′Q′R′ ​ are D′(−1, 1) , E′(1, 1) , and F′(−1, 6) . Which reflection results in the transformation of ​ ​ ​ △DEF ​ ​ ​​ to ​ ​ ​ △D′E′F′ ​ ​ ​​? reflection across the x-axis reflection across the y-axis reflection across y = x reflection across y=−x