Here are the 4 names for the first angle: (Others are similarly named.)
∠ABC
∠CBA
∠B
∠1
Acute: 4, 5
Right: 1
Obtuse: 2, 6
Straight: 3
_____
Note that only angle 1 is known to be a right angle, because it is marked as such. The others appear to have a particular measure, but since they don't have any specific indication of their measure, the appearance cannot be taken at face value. (We suspect you're supposed to use the appearance to answer this question, but don't get in that habit.)
