Injured Player without Substitute

The home team has only nine players at the game. In the bottom of the third inning, the runner at first base (R1) safely steals second base, but is badly injured on the slide.
 
Since there are no substitutes available for the home team, what does the umpire do?
A) The game is immediately forfeited.
B) The game is forfeited when the home team returns to defensive and cannot put 9 players in the field.
C) The game can continue with eight players.
 
What to do with the runner at second base?
A) Since there is no legal substitute for R1, he is called out
B) The defensive coach chooses a player to run for R1
C) The offensive coach chooses a  player to run for R1
D) R1 is replaced by the last batted out
E) R1 is replaced by the most recent batter not on base
 
Call
In NF, and only in NF, a team can play with eight players (NF 4-4-1F and Casebook 4.4.1B).
 
If a player has reached base but must be substituted for when there are no longer any legal substitutes available, the player is replaced by the most recent batter not on base (NF 4-4-1Note).
 
In the situation below, the game can continue with eight players (answer "C"). R1 is replaced by the  most recent batter not on base (answer "E").