Consider the formula: ( k = a⁴b⁵10 ). Given that ( b ) varies with respect to ( t ), and ( a ) stays constant, the derivative ( fracdk/dt ) is:
a. ( 0 )
b. ( 4a⁴b⁵10 )
c. ( 5a⁴b⁵10t )
d. ( 10a⁴b⁵10t⁴ )