### Solution:

Concept: Only right angles have a value of 90˚. Between 90 and 180 degrees are obtuse angles. Acute angles range from 0 to 90 degrees. Only straight angles have a value of 180. Reflex angles range from 180 to 360 degrees.Obtuse angles are always in the range of 90° to 180°. Since the marked angle is less than 90 degrees, we can rule out the idea that it is an acute angle.

The acute angle comes next. Acute angles range from 0 to 90 degrees. The angle indicated in the picture is also clearly greater than 90 degrees, as can be seen. Therefore, it is not an acute angle.

The only angle that is equivalent to 180 degrees is a straight angle. If we consider any point on the line to be the angle's vertex, we can think of it as the angle produced by the line. Therefore, a straight angle is one in which the vertex and both arms are located on the same straight line. The arms themselves are perpendicular to one another, but we can see that the vertex of the specified angle is located on the same line as both of them over here. As a result, none of the three are located on a single straight line, and as a result, the angle indicated is not a straight angle.

However, up until this point, we have come to the conclusion that it is neither larger than 90 nor smaller than it. In actuality, it appears to be exactly equal to 90 degrees, because right angles are angles that are entirely identical to 90 degrees.

Hence the correct answer is option 1.