The flaw lies in the conclusion (C), which does not logically follow from the premises (A) and (B). Just because the first premise states that taking the bus leads to being late, it does not mean that not taking the bus guarantees not being late. The argument incorrectly assumes that the only factor determining lateness is taking the bus, without considering other potential causes or variables that could lead to being late. It oversimplifies the situation by neglecting other possible influences on timeliness, such as traffic, unexpected delays, or alternative modes of transportation.
To make a valid argument, additional premises or evidence would be needed to establish a direct causal relationship between not taking the bus and avoiding lateness while accounting for other potential factors.