. . . . . . . . you read, you cannot pass.

A. Till

B. Unless

C. When

D. If

Answer: Option B

Solution(By Examveda Team)

We use the conjunction 'unless' to mean 'except if'. The clause which follows unless is a subordinate clause (sc): it needs a main clause (mc) to make a complete sentence. When unless comes before the main clause, we use a comma.
Example: Unless it rains, we'll go for a picnic by the river tomorrow.