Selling stock - Specific id vs. FIFO vs average cost

[LCP]

I believe average cost only applies to mutual funds.

My question is re shares of stock ...... can an investor who bought three lots of 100 shares and then sold 100 shares choose to sell, for example, 25 from lot #1, 60 from lot #2 and 15 from lot #3?

[Bees Knees]

You always have the option of using the Specific Identification Method IF you can prove the specific cost basis of each share sold.

[WhiteOleander]

It is also my understanding that the shares must be identified at the time of sale, not later when the sales are being reported.