Correct option is A
The correct substitution of the highlighted words is (a)
through deserts on.
Explanation:
· Use
through (not
throughout) for movement from one side to the other/across the interior of a place: “walk
through the desert.”
Throughout means “in every part of/at all times,” which doesn’t fit a path of movement.
· Use the preposition
on with modes of movement: “
on foot,” “
on bare feet.” The phrase “by bare feet” is incorrect because
by typically marks agency/instrument (by car/by bus/by John), whereas idiomatically we say
on foot.
· “Though” in (d) is a conjunction of contrast, not a preposition of movement, so it is wrong here.
Grammatical rule used:
·
Prepositions of movement vs. extent:
through = movement within/into and out of an area;
throughout = entire area or duration (extent), not path.
·
Fixed expression for pedestrian travel:
on foot (and by extension
on bare feet), not
by foot.
Example (rule):
· We trekked
through the forest
on foot before sunset.
Information booster / exceptions:
· In standard usage,
on foot is preferred over
on feet; “barefoot” as an adjective/adverb is also idiomatic: “walk through the desert
barefoot.” Examination options, however, often test the prepositions (
through +
on).