Select the option that can be used as a one-word substitute for the italicised segment in the given sentence.
Tin is easy to shape in any desired form.

The correct option is malleable.

Explanation:
The phrase "easy to shape in any desired form" describes a material that can be hammered, pressed, or rolled into thin sheets or various shapes without cracking or breaking. The most precise one-word substitution for this definition is malleable.

Let us look at the meanings of the given options:
• Malleable: Capable of being shaped, hammered, or extended by physical pressure without cracking.
• Rigid: Stiff and unyielding; not pliable or flexible.
• Immutable: Unchanging over time or unable to be changed.
• Gullible: Easily persuaded or tricked into believing something.

Therefore, malleable is the correct one-word substitute for the italicised segment.