Which of these nonterminating decimals is a rational number?

0.78567532...

0.34343434.....

0.0203040...

0.35706532....

The nonterminating decimal that is a rational number is 0.34343434.....

This is because the repeating pattern of "34" indicates that the decimal can be written as a fraction. To find the fraction equivalent, the repeating digits should be represented by "x". So, we have:

0.34343434.... = 0.34x

Multiplying both sides by 100 to eliminate the decimal point:

100(0.34343434....) = 100(0.34x)

34.34343434.... = 34x

Subtracting the left side from the right side to eliminate the repeating part:

34x - 0.34343434.... = 34.34343434.... - 0.34343434....

33x = 34

x = 34/33

Therefore, 0.34343434.... is a rational number because it can be written as the fraction 34/33.