ANSWER
B) 15
EXPLANATION
The given polynomial is
[tex]23 {x}^{5} + 12 {x}^{2} + 19 { x }^{3} + 15 {x}^{6} [/tex]
We arrange this polynomial in ascending powers of x to obtain the standard form;
[tex] 15 {x}^{6} + 23 {x}^{5} + 19 { x }^{3} + 12 {x}^{2}[/tex]
The degree of this polynomial is 6.
The coefficient of the leading term is 15