I want to connect my guitar to MacBook pro and start recording with garage band. But i am not able to find ''Line In " option in the sound preferences. i am using macbook pro MD101HNa and macOS sierra latest versions. help me out people.
Your 13" MBP doesn't have a Line In jack. The headphone port is also not a combi, so you can't use a splitter.
If you want to record with Garageband, you'll be best off using an external DAC. Failing that, you could get something cheap like a USB>Audio converter, but the quality isn't likely to be as good.
A USB device would give you as good results as you'd likely get from a built-in line-in jack on an older Mac. The one linked above doesn't do stereo in, but this one does: http://a.co/c2dJ9vP