Direction: Choose the correct Preposition from the options given below to…

Concept: In English, "since" marks a specific point in time — a year, date, day, or moment — from which an action or state began and has continued, typically with the present perfect or present perfect continuous tense. "For" marks a duration or span of time (a number of hours, days, months, or years), not a fixed point.

Application: The sentence uses the present perfect continuous tense ("has been working"), describing an action that began in the past and is still continuing. The blank is followed by "2019", a specific calendar year — a point in time rather than a duration. Because the reference is a point in time, the sentence needs "since": "She has been working here since 2019."

Cross-check — contrast each option by its own value:

• "For" would require a duration, e.g. "for six years," not a fixed year like 2019.

• "From" usually pairs with "to"/"till" (e.g. "from 2019 to now") and does not stand alone with the present perfect continuous to mark unbroken duration.

• "By" marks a deadline for a completed action (e.g. "by 2019"), which conflicts with the ongoing sense of "has been working".

Result: the sentence reads "She has been working here since 2019."