Which type of wireless encryption is used for WPA2 in preshared key mode? 

Answer options:

A. AES-128
B. TKIP with RC4
C. AES-256
D. RC4

C

We can see in this picture we have to type 64 hexadecimal characters (256 bit) for the WPA2 passphrase so we can deduce the encryption is AES-256, not AES- 128. 

Reference: https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/67134-wpa2-config.html