Which of the following is used by IEEE 802.11n to achieve high throughput through the use of multiple antennas for transmission and reception?
1) Orthogonal Frequency Division Multiplexing (OFDM)
2) Multiple Input Multiple Output (MIMO)
3) Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
4) Direct Sequence Spread Spectrum (DSSS)