In which does y vary inversely with x

Answer:
b
Step-by-step explanation:
k= xy
where x= 1, 4.5, 6 and y= 18, 4, 3 respectively
1k=2k=3k
k= 1 × 18= 18
k= 4.5 × 4= 18
k= 6× 3= 18