(1) when, in effecting entry or while in the dwelling or in immediate flight, he or another participant in the crime:
(a) is armed with a deadly weapon or explosive; or
(b) causes physical injury to a person who is not a participant in the crime; or
(c) uses or threatens the use of a dangerous instrument; or
(d) displays what is or appears to be a knife, pistol, revolver, rifle, shotgun, machine gun, or other firearm; or
(2) the burglary is committed by a person with a prior record of two or more convictions for burglary or housebreaking or a combination of both; or
(3) the entering or remaining occurs in the nighttime.
(B) Burglary in the first degree is a felony punishable by life imprisonment. For purposes of this section, "life" means until death. The court, in its discretion, may sentence the defendant to a term of not less than fifteen years.