D

To identify isobars, we need to find pairs of elements that have the same mass number (the total number of protons and neutrons) but different atomic numbers (number of protons).

- **Option A:** The images likely represent isotopes of hydrogen. They have the same atomic number (Z = 1) but different mass numbers. Thus, they are not isobars.

- **Option B:** Similarly, the elements in this option are likely isotopes of carbon, having the same atomic number (Z = 6) but different mass numbers. Therefore, they are not isobars.

- **Option C:** Represents isotopes of silicon and phosphorous, which do not have matching mass numbers, hence they are not isobars either.

- **Option D:** This pair consists of phosphorus-30 ($^{30}_{15}P$) and silicon-30 ($^{30}_{14}Si$), which share the same mass number (30) but are different elements (Z = 15 for phosphorus and Z = 14 for silicon). Therefore, they qualify as isobars.

Hence, the correct answer is D.