Correct option is B
(A) is true, but (R) is false.
Assertion (A) is correct because reading and writing skills do help in critical thinking at the primary level. Critical thinking is the ability to analyze information, evaluate arguments, and draw conclusions. Reading and writing skills help students to develop these skills by providing them with the opportunity to practice these skills.
However, Reason (R) is false because critical thinking is not a sub-skill of reading and writing. Critical thinking is a separate skill that is developed through a variety of experiences, including reading and writing.