Which IEEE 802.11 physical layer (PHY) specification includes support for and compatibility with bot

Which IEEE 802.11 physical layer (PHY) specification includes support for and compatibility with both ERP and HR/DSSS?

A. VHT (802.11ac)

B. OFDM (802.11a)

C. DSSS (802.11-Prime)

D. HT (802.11n)