Since a phone with one payment plan and one accessory is given away at random, we need to consider only the rows where the payment plan is 1 and the column where the accessory is a headset. Looking at the table, we can see that there is only one phone that meets these conditions, and it is a Brand B phone with a headset. Therefore, the probability that a phone with one payment plan and one accessory is given away at random and is a Brand B phone with a headset is 1/10 or 0.1.