In the solution given here, r is squared,.. i want to know why it is squared? (i've marked it in pencil)please see.

(A) (A) (+1, +1, +1) (-3,-3,-3) (D) (C) wires having resistances R and 2R are connected in parallel, then ratio of heat gen. in R and 2R is -2,-2,-2) ne Ca 27. (A (B) 2:1 (A) 3:2 (D) 4:1 C) 1:4