Step 1: Sentence Interpretation.
The sentence describes a person who is positioned next to another, providing assistance during a critical situation. The appropriate preposition should denote accompaniment or collective action in an event or crisis.
Step 2: Option Evaluation.
- "With" signifies adjacency or togetherness, aligning perfectly with the context.
- "In" denotes location or a state, which is irrelevant here.
- "For" indicates purpose or endorsement, but not the intended meaning.
- "By" suggests closeness but lacks the connotation of joint support.
Step 3: Resolution. "With" accurately expresses solidarity or support during a crisis.Therefore, the correct choice is 1. with.
Final Determination: \[\boxed{\text{The correct answer is 1. with.}}\]