Touchback ??

[l3will]

Lawyering up....key... team possession....

Rule 2-13-4...Force is not a factor:
b. When a backward pass or fumble is declared dead in the end zone of the opponent of the player who passed or fumbled, with no player possession.

Rule 8-5-3... It is a touchback when:
c. A fumble is the force, or a muff or bat of a backward pass or a fumble after either has touched the ground is the new force, which sends the ball to or across the the opponent's goal line and provided such opponent is in team possession or the ball is out of bounds when it becomes dead or behind dead on or behind its goal line.

By these rules... It is a touchback...

No player possession... Team A still had team possession.

I'll let you read the whole rule...
Rule 8-5-2 ... It is a safety when:
b .....provided the ball becomes dead there in his team's possession...