finding out what the most profitable product in terms of money in 2016?

id  product account year cost

1   crisps  100 2017    4   
2   lipsticks   103 2017    3   
3   chocolate_bars  107 2016    1   
4   chocolate_bars  107 2016    1   
5   crisps  115 2018    4   
6   chocolate_bars 111  2017    1   
7   lipsticks   408 2016    2   
8   lipsticks   408 2015    2   
9   lipsticks   592 2017    2   
10  chocolate_bars  128 2016    1   

This is my data set I was curious how you would work out what the most profitable product was in 2016

Note: this data-set has been significantly shortened for the benefit of asking this question