According to the Endosymbiotic Theory, Why Was It Adaptive for the Larger

Multiple Choice

According to the endosymbiotic theory, why was it adaptive for the larger (host) cell to keep the engulfed cell alive, rather than digesting it as food?

A) The engulfed cell provided the host cell with adenosine triphosphate (ATP) .
B) The engulfed cell provided the host cell with carbon dioxide.
C) The engulfed cell allowed the host cell to metabolize glucose.
D) The host cell was able to survive anaerobic conditions with the engulfed cell alive.
E) The host cell would have been poisoned if it had digested the engulfed cell.