The correct option is C 3
The degree of a polynomial is the greatest of the sum of the powers (exponents) of the variables used in the various terms of the given polynomial:
The terms in the given polynomial are 5x; xy2 and 10yz
The sum of powers of variables in 5x = 1
The sum of powers of variables in xy2 = 1+2 = 3
The sum of powers of variables in 10yz = 1+1 = 2
Hence the degree of the polynomial = 3