C) rhombus.
lines of symmetry can only go through symmetrical shapes. rhombuses are not symmetrical.
If it took you (one person) 3 days to build a doghouse, then it should take 2 people to build it in half the time. So all we have to do is split 3 days in 2.
3/2 = 1.5
So it would take 1 1/2 days or 36 hours for 2 people to complete the doghouse.
18/1
36/2
72/4
...and many more....
The circumference is the correct.
It can be found using the formula,