It is given that the decay is exponential. It is also given that the decrease is constant at a rate of 7.9% per year. This can be rewritten as

Now, we know that right now there are atleast 26 million of the species. Thus, the starting or the initial amount of the decay is 26.
Therefore, this part of the inequality will be:
, where the minus sign before the 0.079 denotes the decay.
Also, we know that the population cannot go below 2 million. Therefore, we will have:
.
Combining the above two we get:
, and

Thus, out of the given options, the last option is the correct option.