Answer:
The correct option is B. The length of OB' is 3 units.
Explanation:
The rule of dilation is D₀,₄. It means dilation by scale factor 4 with center of dilation is origin.
![\text{Scale factor}=\frac{\text{Distance between center and any point of the image}}{\text{Distance between center and corresponding point of the Preimage}}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qpywvh5z82ggljld80lxcunisesa2c5kqj.png)
![\text{Scale factor}=(OB')/(OB)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/27hmnem63lucu1c46af0jol0xhvugg3huj.png)
![4=(OB')/((3)/(4))](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fe3qsgnovq1jnretefgehqie6q7s7tkepu.png)
![4* (3)/(4)=OB'](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jwjkta0ybiuyr4tp5pbl7gtbuui8by25wh.png)
![3=OB'](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8vo9yx8ilsme5my4jg1b8l0xlna42logxq.png)
The length of OB' is 3 units. Therefore the correct option is option is B.