Select the most appropriate word to fill in the blank.

The boy was leaning against the pillar ______ his hands ______ his pockets.

with; in

The correct answer is with; in.

The preposition "with" is used to indicate connection or association. In this sentence, the boy is connected to the pillar by leaning against it. The preposition "in" is used to indicate location or containment. In this sentence, the boy's hands are contained in his pockets.

The other options are not as appropriate.

• The preposition "for" is used to indicate purpose or reason. It is not clear how the boy's hands are connected to the pillar for his pockets.
• The preposition "into" is used to indicate movement from the outside to the inside. It is not clear how the boy's hands are moving into his pockets.
• The preposition "from" is used to indicate movement from the inside to the outside. It is not clear how the boy's hands are moving from his pockets.