This has to do with the algorithm of treating shock. Septic (a type of distributive) shock as well as hypovolemic shock are treated with IV fluid resuscitation (FA2020 p310). Crystalloid fluids are first-line choice, and normal saline (0.9%, isotonic) is first-line specifically in cases of shock.
5% dextrose in water and 0.45% saline is hypertonic and not useful here.
5% dextrose alone is isotonic in the bag but physiologically hypotonic. It is more often given for fluid replacement after severe dehydration.
0.45% saline only is hypotonic and not useful here.
3% saline is hypertonic and not useful here.