Estimation and Error

Answer : C

For A, it should be 0.05.
For B, it should be 0.0499.  We do not count the red 0.
For D, it should be 0.049877.

For instance, I would like to correct the following to 3 significant figures.

1) 0.043249 à 0.0432  

We do not count the red 0s since there are no numbers other than 0 before them.

2) 12.056 à 12.1          

We count the red 0 since there are numbers other than 0 before it.