When measureing and presenting the result, the last digit of the number carries the uncertainty. That is, the last digit is not exactly known. We can see that the ruler goes from 0 cm to 1 cm and we have 9 mark in between, one for each 0.1 cm increment.
The green bar goes from the 0.0 mark until between the 0.9 and 1.0 mark.
This means that we know for sure that the measure of the green bar is between 0.9 and 1.0, that is, the measure is 0.9 followed by something. So, the digit "9" is known for sure. But, the last digit of a measure is the one that is uncertain, so we can pick one extra digit then. From the place between the 0.9 and 1.0 that the gree bar ends, we could guess it is 2, as the options show, so the measure would be 0.92.
The mening is then that we knoe 9 for sure and 2 we don't know for sure (for someone, it could be 3 instead), but we should present the first uncertainty.
Thus, the correct option is 0.92 cm.