Let the initial price be 'P' and initial sales be 'S'

So, the initial revenue C = P*S

Now,

P_{new} = 1.3P and S_{new} = 0.8S

$\therefore$ C_{new}_{ }= P_{new}*S_{new} = 1.3P*0.8S = 1.04C

So, there is a 4% increase in total revenue.

**C is the answer.**