Loss of Down
 

Sit.
4th and 5 from the 50. A runs the option and advances the ball to the 30 where they pitch the ball forward and a flag is thrown.

Enforcement??? 1st and 10 from the 35 for A as they have already gotten the 1st down?

Since, after enforcement of the 5 yard penalty from the spot of the illegal pass the ball is beyond the line to gain it will be 1st and 10. The loss of down provision has no effect. Since the penalty includes a loss of down, if time had expired during the down the period would NOT be extended.

Or had the line to gain not been made after the penalty, it would be B's ball.