Some boys are men. No man is black

Conclusions:

1. Some boys are not black

2. Some men are boys

From solving 1 and 2 we get,

1.

5a(a-3)-3(a-3) = 0

(5a-3)(a-3) = 0

a = 3 or 3/5

2. 

3b(b+2)-1(b+2) = 0

b = -2 or b = 1/3

Here when a = 3, a > b for b = -2 and b = 1/3

when a = 3/5. a > b for b = -2 and b = 1/3.

Hence, it is clear that a > b. 

From given statements, we can conclude that

N > C < T < L= P > Q  .....(1)

Here given that C > Y but in eq(1) we got that C < T < T <= P => Y is definitely less than P.

So only conclusion B is True.

From both statements we cannot conclude the train catched by Harish

Since he missed at 4.15 and train coes at 4.30, 4.45, 5.00,...

But in B given that he didn't catch the train at 4.45 and after that.

So both statements A & B together are not sufficient to answer the question.

From statement B, 

As the value of L = 0, the value of KL = 0.

Hence only statement B is sufficient.

From statement A, we know that Pipe A can fill the tank in 40 hours. However, this information is not sufficient as we do not have the data for Pipe B. Hence, statement A alone cannot answer the given question.

From statement B, we know that Pipe B is one third as efficient as pipe A. However, we do not know the rate at which Pipe A fills the tank. Hence, we will not be able to find the rate at which Pipe B fills the cistern. Therefore, statement B alone is not sufficient to answer the question.

Now, if we combine the two statements, we know that Pipe A take 40 hours to fill the cistern.
Pipe B takes 120 hours to fill the cistern.

If they worked alternately, then either Pipe A could have started the cycle or Pipe B could have started the cycle.

If Pipe A started the sequence of filling alternately, then at the end of two hours, the two pipes together would have filled 1/40 + 1/120 = 1/30  th of the tank in an hour. Or the cistern will fill in 30 hours.

If Pipe B started the sequence, then at the end of 2 hours, the two pipes together would have filled 1/120 + 1/40 = 1/30 th of the tank in an hour. Or the cistern will fill in 30 hours.

As the answer obtained irrespective of which pipe started the sequence is the same, the correct answer is (3) - i.e., both the statement are sufficient to answer the question.

There is no indication that Indian scientists are incapable of developing enzymes. There could be any number of reasons why Indian scientists used Russian enzymes.

So conclusion A does not follow.

In addition, cost is not discussed in the passage at all. There is no mention of a correlation between cost and extraction of proteins.

Thus, conclusion B does not follow either.

I.  (a - 3)(a - 4) = 0

=> a = 3, 4

II.   (b - 2)(b - 1) = 0

=> b = 1, 2

=> a > b