Correct Answer: $29:34$

Solution : As per the given graph:
The marks of students in Biology in 1st term = 90
The marks of students in Biology in 2nd term = 55
The average marks of students in Biology in both terms
= $\frac{\text{ 1st term marks + 2nd term marks}}{ 2}$
= $ \frac{90+55}{ 2}=\frac{145}{2}$
The marks of students in Maths in 1st term = 100
The marks of students in English in 1st term = 55
The average marks of students in Maths and English in 1st term
= $\frac{\text{ 1st term marks in Maths + 1st term marks in English}}{ 2}$
= $\frac{100+70}{ 2}=\frac{170}{2}$
The required ratio = (The average marks of students in biology in both terms) : (The average marks of students in Maths and English in 1st terms)
The required ratio = $\frac{145}{2}$ : $\frac{170}{2}$
The required ratio = $29:34$
Hence, the correct answer is $29:34$.