Problem 45773. Mo money, mo math #2! (★★★)

(adapted from Prob 9 Cody team)

You have a matrix for which each row is a person and the columns represent the number of quarters, dimes, nickels and pennies that person has (in that order). What is the row index of the person with the most money?

Note for those unfamiliar with American coins: quarter = $0.25, dime = $0.10, nickel = $0.05, penny = $0.01.

Example:

 Input  x = [ 0 0 0 3; 1 0 0 0; 0 1 0 0]
 Output y = 2

since the first person will have $0.03 and the second person will have $0.25, while the third person has $0.10. Thus, the second person has the most amount.