I don't think you have attached the options, but I'll show you a shortcut method to solve this anyway (which may or may not be in the multiple choice answers):
1. Compute 12*5
2. Add a zero at the end of the product
Another way (which is slightly longer):
1. Split 50 into 10*5
2. Multiply 12*5 to get 60
3. Multiply 60*10 to get 600
