why do you think the options under A6 are not showed? I need to enable the I2C options to use a LCD. I DON'T understand what is happening.
EDIT: I was completely wrong. This answer is correct.
You might be using an older version of raspi-config or something similar. Try selecting the "update" option and see if it shows the I2C enable option now. If not, the desktop application "Raspberry Pi Configuration" should definitely have it.