5. The values of Zi, Zr and Ze as measured by four students P, Q, R and S are tabulated below: [CBSE Foreign 2012 Students P Q R S Angles Zi 30° 30° 30° 30° Lr 16° 18° 20° 22° Le 32° 31° 29° 31° The student who performed the experiment most carefully: (a) P (c) R (b) Q (d) S