The answer is 63 cm bc 30 60 90 triangles have a rule where the short leg is x longer is x√3 and the hypotenuse is x2 you can see this if you imagine the triangle as equilateral then cutting it in half
Because if you start with one dollar and by day 3 you get 301 dollars and option A only gives you 8 cents on day 3 you get more money by the end of the month if you choose option B.