Concept:
- 'Else' means 'otherwise', and it is used after a command or instruction to warn of a negative consequence if the instruction is not followed.
Step 1: Read the structure of the sentence
"Make haste, ___ you will miss the fashion show" is a command followed by a warning of what will happen if the command is not obeyed.
Step 2: Eliminate words that do not fit a warning structure
'Either' is used to present alternatives, not warnings. 'So' shows a result following an action, not a warning against inaction. 'On' is a preposition and does not fit grammatically here at all.
Step 3: Match the correct connector
'Else' correctly links the command 'make haste' to the negative consequence 'you will miss the fashion show', exactly like saying 'otherwise'.
Final Answer: else