Select the option that will improve the underlined part of the given sentence.
My friend vanished when the goons came to fight with me.

The correct option is: disappeared when the thugs arrived

Step-by-step Explanation:

1. Analyze the original sentence:
The given sentence is: "My friend vanished when the goons came to fight with me."
We need to find the option that best improves or correctly replaces this underlined part while maintaining the original context and meaning.

2. Examine the key vocabulary:
- Vanished: This verb means to disappear suddenly and completely from sight. Its direct synonym is "disappeared".
- Goons: This noun refers to bullies, ruffians, or hired thugs. A direct synonym is "thugs".
- Came to fight with me: This clause describes the arrival of these individuals, which is succinctly captured by "arrived".

3. Evaluate the given options:
- mobilised when the thugs arrived: "Mobilised" means to organize or prepare forces for action, which contradicts the action of vanishing/running away.
- disappeared when the thugs arrived: This correctly replaces "vanished" with "disappeared" and "goons" with "thugs", preserving the original meaning of the sentence.
- condemned when the thugs arrived: "Condemned" means to express complete disapproval of, which does not fit the context of the situation.
- attacked when the thugs arrived: "Attacked" means to initiate an assault, which is opposite to the meaning of vanishing.

Thus, the option that correctly and contextually improves the underlined phrase is "disappeared when the thugs arrived".