The data is text tells that

`R_1 =2*R` and `R_2=R`

The equivalent resistance of the two resistors connected in series is

`R_(eq) =R_1+R_2 =2R+R =3R`

As Ohm law states the current is the same in both `R_1` and `R_2` :

`I =U/R_(eq) =U/(3R)`

The power (rate of heat generation) in resistor `R_1`  is

`P_1 = I^2*R1 =(U/(3R))^2 *(2R) =(U^2/(9R^2))*2R =(2/9)*U^2/R`

The power in resistor `R_2` is

`P_2 =I^2*R2 =(U/(3R))^2 *R =(U^2/(9R^2))*R = (1/9)*U^2/R`

Therefore

`P_1 =2*P_2`

The correct answer is B) twice that in 2