Option 1 -> "Standing with" suggests accompanying or being alongside, but is less idiomatic for expressing support during difficult times.
Option 2 -> "Standing in" is grammatically incorrect in this context and doesn't convey any meaningful relationship.
Option 3 -> "Standing for" means representing or advocating for something/someone, but doesn't express emotional support during a crisis.
Option 4 -> "Standing by" is the correct idiom that means to support, remain loyal to, or stay with someone during difficult times.
Hence, Option 4: by -> "Standing by someone" is a common English idiom that specifically means to support and remain loyal to someone during challenging or difficult situations, making it the perfect choice for describing support during a crisis -> correct