The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
I have been / reading this book / since / two days.

Correct option is B

Option (b) contains an error.
Explanation: The preposition ‘since’ is used with a specific point in time, whereas ‘for’ is used for a period of time. “Two days” is a duration, not a specific point, so “for” should be used instead of “since.”
Grammatical rule used:
· Since → used with a specific starting time (e.g. since Monday, since 2010)
· For → used with a duration (e.g. for 2 hours, for 10 days)
Example:
Incorrect – I have been reading this book since two days.
Correct – I have been reading this book for two days.
Information Booster:
Common error in spoken English: using "since" with duration. Always match prepositions correctly with time expressions.