Correct : a

To find the correct propositional logic representation, let us analyze the conditional structure of the statement:
• Identify the Propositions:
    • p: Fail grade can be given.
    • ¬p: Fail grade cannot be given (the negation of p).
    • q: Student scores more than 50% marks.

• Analyze the Phrase Structure:
The statement is written as: "Fail grade cannot be given when student scores more than 50% marks."
In logic, the word "when" introduces the sufficient condition (the premise or antecedent). The sentence can be rephrased into standard "If... then..." form without changing its meaning:
    "If a student scores more than 50% marks, then a fail grade cannot be given."

• Map to Logical Operators:
    • Antecedent (If part): q
    • Consequent (Then part): ¬p
    • Conditional operator: →

Combining these components gives the logical implication expression: q → ¬p.

Thus, the correct representation is option (a).