Four Flasks Are Prepared with a Broth That Supports Microbial

Multiple Choice

Four flasks are prepared with a broth that supports microbial growth. Broth A is boiled and then sealed to prevent the entry of air. Broth B is boiled and left open to the air. Broth C is boiled and left open, but the flask is fitted with an S-shaped neck. Broth D is boiled, left open to the air, and fitted with an S-shaped neck, but after two days the neck is removed. If the broths are examined after four days, which ones will contain living microorganisms?

A) All broths will contain microorganisms.
B) None of the broths will contain microorganisms.
C) broths B & D
D) broths A & C
E) broths B, C & D