Some people believe that to have an effective conversation，a distance of about 20 inches(51 centimeters)between the two parties involved is required．In certain cultural groups．however，the normal conversational distance is in the range of 14 to 15 inches(36 to 38 centimeters)：and some group say 9 to 10 inches(23 to 25 centimeters) is ideal．People from some cultural groups may keep a door open during a negotiation．whereas others may prefer to close the door．Some people feel they should be separated from another person by a desk．This area of nonverbal communication is important for cross-cultural communication．It is known as______．
A．proxemics
B．personal space dynamics
C．posturing
D．linguistics