A triangle can be

For a proper triangle the sum of all interior or internal angles should be equal to 180°.

Now let us take each option separately,

For option A:

110° + 40° = 140° and so the third angle is 40°.

For Option B:

70° + 115° = 185° which is greater than 180° which is not correct.

For option C:

135° + 45° = 180°. Here the sum is already 180° without considering the third angle which is incorrect.

For option D:

90° + 90° = 180°. Here the sum is already 180° without considering the third angle which is incorrect.

So it is clearly observed that only option A is satisfying the angle condition of the triangle.

So the correct answer is A.