Choose the option which best replaces the underlined phrase.
When Dr. Sapra came to the school in 1995, Dr. Anand had already been teaching there since five years.

In the sentence, the phrase "since five years" is incorrect.

We use "for" with a duration (e.g., for five years). We use "since" with a point in time (e.g., since 1990).

So, the correct replacement should be Option 2: had already been teaching there for five years

Incorrect Option:

1. have already been teaching there for five years

Incorrect tense - “have” is present perfect, but the main clause is in the past.

3. has already been teaching there since five years

Wrong tense ("has" is present perfect), and again "since five years" is incorrect usage.