It depends, in the best case 15 seconds. But usually a few minutes and when the Mars is behind the sun, you can't use light.

You are not really cut out, but the communication is not interactive and you can only play round based online games. I still hope quantum entanglement can be used as a communication tool.

Quantum entanglement cannot be used to transmit information. This would fundamentally violate relativity and all modern understandings of physics. Additionally, sending a signal to Mars takes much longer than 15 seconds (still over 4 minutes at the closest approach).

It could be used to transmit information, just not faster than the speed of light.

Quantum entanglement might still be used for communication. See quantum cryptography

It's more like 4-20 minutes.