Fill in the blank with the appropriate modal :

Till 1990, I ____ read without glasses.

(A) should
(B) shall
(C) could
(D) will

Choose the correct answer from the options given below:

(C) Only

The correct answer is Option (1) → (C) Only

The sentence refers to an ability in the past ("Till 1990").

• The correct modal verb to express past ability is "could".

OTHER OPTIONS

• (A) should → Incorrect, as "should" is used for obligation or advice, not ability.
• (B) shall → Incorrect, as "shall" is used for future actions or formal obligations.
• (D) will → Incorrect, as "will" refers to the future, but the sentence is about the past.

Thus, the correct sentence is: "Till 1990, I could read without glasses."