Answer: Frogs will be last to die due to increase in acid rain.
Explanation: Acid rain is a form of rain with high concentration of hydrogen ions and is acidic in nature. pH of these rains is low.
pH is the negative logarithmic of hydrogen ion concentration. It is known as power of hydrogen.
Mathematically,
![pH=-\log[H^+]](https://img.qammunity.org/2018/formulas/chemistry/high-school/9so9u3mmeurzbcqkpf3jt5b89ctmc03tdp.png)
More the hydrogen ion concentration, low will be the pH and vice-versa.
For the given question, the animal which has the lowest value of pH will be able to tolerate the acid rain more and will be last to die.
From the tolerance range of the animals, frogs has the lowest pH for survival which is 4 and it can bear more acid rain than the rest of the animals will be the last to die.
Hence, the correct answer is Frogs.