Let 'a' and 'b' be the marks obtained by Romit in Verbal English and Logical Analysis respectively. It is given that,

a + b + 70 = 210

a + b = 140.  ... (1) 

It is observed that one-third of the marks obtained by Romit in Logical Analysis is greater than half of his marks obtained in Verbal English By 5.

$$\dfrac{b}{3} - \dfrac{a}{2} = 5$$

$$2b - 3a = 30$$   ... (2)

On solving equation (1) and (2) we get b = 90 and a = 50. 

  Hence, the difference between the marks obtained by him in Mathematics and Verbal English = 70 - 50 = 20.

Therefore, option C is the correct answer.