I forgot to top - up my card ! " And with no small change with us , we were forced to walk from the apartment beside Greenview Sec all the way to Pasir Ris MRT station . I could have taken the bus , but being a good person that i am , i walked with my sister .

Generate a question about the above context.
Why may the narrator 's legs be so sore and tired ?
Pick from: [I] They took a car .; [II] They opted to walk .; [III] They took a boat .; [IV] They took a train .;