Answer:
d) At the end of each period
Step-by-step explanation:
"Total manufacturing cost is the aggregate amount of cost incurred by a business to produce goods in a reporting period. [...] The more common usage of the term is that total manufacturing cost follows the first definition, and so is the amount charged to expense in the reporting period." This is why AllWeather estimates about 100 production runs per year.
Reference: Bragg, Steven. “Total Manufacturing Cost.” AccountingTools, AccountingTools, 21 Jan. 2019