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1.A. Floating IP address are used on behalf of instances B.

FIP  provides inbound connectivity via Neutron Routers DNAT

2.Floating IP address are translated to fixed IP address to allow an instance initiate external communication

Bipin's  answer above is incorrect. VM gets outbound connectivity via Neutron Routers SNAT. 
Thus VM may work with Net without floating IP, but is NOT visible from external world.

1.A. Floating IP address are used on behalf of instances B.

FIP  provides inbound connectivity via Neutron Routers DNAT

2.Floating IP address are translated to fixed IP address to allow an instance initiate external communication

Bipin's  answer above  is incorrect. VM gets outbound connectivity via Neutron Routers SNAT. 
Thus VM may work with Net without floating IP, but is NOT visible from external world.