The following data pertains to activity and costs for two months: June July Activity level in units........... 10,000 12,000 Direct materials .................. $16,000 $ ? Fixed factory rent ............... 12,000 ? Manufacturing overhead .... 10,000 ? Total cost ........................... $38,000 $42,900 Assuming that these activity levels are within the relevant range, the manufacturing overhead for July was: A) $10,000 B) $11,700 C) $19,000 D) $9,300