We are given a diagram. We want to find the line(s) that contain point B and are parallel to CD. To do so we will first recall the definition of parallel lines.
Also, in a coordinate plane, parallel lines have the same slope. From here we will find the coplanar lines with the same slope, so let's first extend the line to observe better.
In the diagram, we have a three-dimensional object, the lines parallel to CD in different planes will run in the same direction, similar to a slope. Since the aquarium is a rectangular prism, we know that BA, FE, and GH are parallel to CD. Among the parallel lines to CD, the line that contains point B is BA, so it fits the required description.
Therefore, we can conclude that there is only one line that contain point B and parallel to CD and this line is BA.
