The correct option is C 38.78 kg < 38.8 kg < 45.4 kg
When we compare the decimals numbers then we move from left side towards the right side.
In 38.8, it has 3 tens, 8 ones and 8 tenths.
In 45.4, it has 4 tens, 5 ones and 4 tenths.
In 38.78, it has 3 tens, 8 ones, 7 tenths and 8 hundredths.
So, 38.78 is the smallest number and 45.4 is the largest number.
Thus, 38.78 kg < 38.8 kg < 45.4 kg.