(a) We can see that,

In the given circles,

One out of two,

Two out of four,

Three out of six,

And,

Four out of eight

Equal parts are shaded respectively.

Hence,

These circles represent.

Also, these fractions are equivalent

(b) We can see that,

In the given circles,

One out of two,

Two out of four,

Three out of six,

And,

Four out of eight

Equal parts are shaded respectively

Hence,

These circles represent

We see, not all these fractions are equivalent.