If output is produced according to Q  4LK, the price of K is $10, and the price of L is $40, then the cost minimizing cost minimizing combination of K and L capable of producing 64 units of output is

A) L  16 and K  1.
B) L  2 and K  8.
C) L  2 and K  2.
D) L  32 and K  32.
E) L  1 and K  16.

To find the cost minimizing combination, we need to use the formula:
MC of K / P of K = MC of L / P of L
Or, MC of K / 10 = MC of L / 40 (since the price of K is $10 and the price of L is $40)
Given, Q  4LK
Or, Q = min(, 4L, K)
Or, Q = min(, 4L, K) (since K is multiplied by )
To produce Q = 64 units of output, we can substitute Q = 64 in the above equation:
64 = min(, 4L, K)
Since we want to minimize the cost, we need to use the lowest possible values for L and K.
For L, we can set L = 16, which gives Q = 4L = 64, and satisfies the equation.
For K, we can set K = 8, which also gives Q = K = 64, and satisfies the equation.
Therefore, the cost minimizing combination is L  2 and K  8.