A conducting square loop is placed in a magnetic field B with its plane perpendicular to the field. The sides of the loop start shrinking at a constant rate \[\alpha \]. The induced emf in the loop at an instant when its side is 'a' is

• A. \[2a\alpha B\]
• B. \[{{a}^{2}}\alpha B\]
• C. \[2{{a}^{2}}\alpha B\]
• D. \[a\alpha B\]