Answer:
The greatest mass among the following measurements is:

Explanation:
I am going to convert each one of these measurements to kilogram, then the biggest value in kg is the greatest mass.
a)

Each kg has
.
So
1 kg -

x kg -

x = 2.
So
b)

Each kg has
.
So
1 kg -

x kg -


This is a smaller mass than a)
c)

Each kg has
.
So
1 kg -

x kg -

x = 9kg.

For now, this is the greatest mass.
d)

This is the greatest mass.