Answer: 1.8
Step-by-step explanation:
First option is wrong because using a scale factor of 1 would result in the same shape.
Second option is wrong because using a scale factor less than 1 would result in shape 2 becoming smaller.
Third option is most likely as shape 1 looks almost double the size of shape 2.
Fourth option is unlikely because shape 2 would have to expand more than 4/3 to be as large as shape 1.
Fifth option is wrong because the scale factor cannot be less than 1.