Final Answer:
The answer is 0, thus the correct option is d.
Explanation:
An integer is a whole number which can be either positive or negative. It has no fractions or decimals and can be written without a fractional or decimal component.
In this question, option a) π (π) is not an integer because it is an irrational number which cannot be expressed as a fraction. Option b) 1/4 is also not an integer because it is a fraction, which means it has a decimal component.
Similarly, option c) 3.175 is also not an integer as it has a decimal component. Lastly, option d) 0 is an integer because it is a whole number with no decimal or fractional component.