Answer:
c. Specific identification and FIFO
Explanation:
Under FIFO company will pick the oldest unit regardless of the method, so it will do no difference while, LIFO under perpetual inventory "jumps" after a purchase to use first these units, leaving portions of previous sales behind.
Under specific identificaion, eahc unit has his own cots. regardless of the method, when selling the COGS will be the specific cost for this units .