The hungry bird finally stopped hovering overhead, so the caterpillar began to inch along the tree branch aReading the paragraph.

We saw it from miles away, sitting atop the crest of a hill. The old walls were crumbling, but you could still see the outlines of the vast parapets and stone towers.

The author is most likely looking at

an old house.
an old castle.
an old mansion.
an old building.gain.

What is the best synonym for inch as it is used in the sentence?

creep
move
walk
slither