Option (c) is correct.
Explanation:
Given that,
Direct materials  = $40,100
Direct labor  = $29,700
Manufacturing overhead  = $21,200
Selling expenses  = $25,600
Administrative expenses  = $32,100
Therefore, the Conversion costs during the month as follows:
=  Direct labor  +  Manufacturing overhead
= $29,700 Â + $21,200
= $50,900