Answer: The figure that has exactly one line of symmetry is B. Pentagon.
Step-by-step explanation: A line of symmetry is a line that divides a figure into two congruent halves that are mirror images of each other. A figure can have zero, one, or more lines of symmetry depending on its shape and orientation. To find the lines of symmetry of a figure, we can use a paper folding method or a reflection test. A paper folding method involves folding the figure along a line and checking if the two halves match up exactly. A reflection test involves reflecting the figure over a line and checking if the image coincides with the original figure.
Using either method, we can see that:
A. Rhombus has two lines of symmetry: one diagonal and one vertical.
C. Rectangle has two lines of symmetry: one horizontal and one vertical.
D. Triangle has either zero or three lines of symmetry depending on the type of triangle. An equilateral triangle has three lines of symmetry: one vertical and two bisecting the angles. An isosceles triangle has one line of symmetry: the perpendicular bisector of the base. A scalene triangle has no lines of symmetry.
B. Pentagon has either zero or five lines of symmetry depending on the type of pentagon. A regular pentagon has five lines of symmetry: each passing through a vertex and the midpoint of the opposite side. An irregular pentagon has no lines of symmetry.
Therefore, the only figure that has exactly one line of symmetry is B. Pentagon, but only if it is an isosceles pentagon.
Hope this helps, and have a great day! =)