To find the 2 significant figures:
A. 45
Since, there are two non zeros 4 and 5.
Therefore, this has 2 significant figures.
B. 90
Since, it has only one non zero digit 9.
Therefore, it has not 2 significant figures.
C. 180
Since, there are two non zeros 1 and 8.
Therefore, this has 2 significant figures.
D. 22.5
Since, there are three non zeros 2, 2 and 8.
Therefore, this has not 2 significant figures.
Hence, the correct options are A and C.
