D. The triangle could be acute or obtuse, depending on the measures of the other two angles.
The ratio of the measure of an exterior angle of a triangle to the measure of the adjacent interior angle is 1:4, which means that for every 1 degree of the exterior angle, there are 4 degrees of the interior angle. However, this does not provide enough information to determine the overall shape of the triangle.
The triangle could be acute (all angles less than 90 degrees), right (one angle equal to 90 degrees), or obtuse (one angle greater than 90 degrees) depending on the measures of the other two angles. For example, if the interior angle measure is 36 degrees, the exterior angle would be 9 degrees, and the triangle could be acute. On the other hand, if the interior angle measure is 144 degrees, the exterior angle would be 36 degrees, and the triangle could be obtuse.