while tracing the path of a ray of light passing through a rectangular glass slab a student tabulated his observations as given below:
S.N.O ∠i ∠r ∠e
I 60⁰ 39⁰ 61⁰
II 50⁰ 36⁰ 51⁰
III 40⁰ 28⁰ 39⁰
IV 30⁰ 20⁰ 31⁰
The correct observation is:
A) I
B) II
C) III
D) IV