Final answer:
The length of B'C' is 3 units.
Step-by-step explanation:
Quadrilateral ABCD undergoes a dilation with respect to point A, with a scale factor of 1/4. To find the length of B'C', we can use the concept of similarity. In a dilation, corresponding sides of the original and dilated figure are proportional to each other. Since the scale factor is 1/4, B'C' would be 1/4 the length of BC. Therefore, B'C' is 3 units long.