A. India, on the other hand, would have adequate young manpower to even overtake China after sometime:
B. But, a direct consequence ofthese is a situation where China would not nay enough young workforce to further develop its economy after a few years.
C. China’s population is much larger thanthat of India.
D. As a result, China has been able to check its population growth effectively.
E. However, in the past two decades or so, China enforced strict measures to control its population growth.

We are looking for the ideal sentence to start the paragraph. Let us look at each of the sentences, 
A. India, on the other hand, would have adequate young manpower to even overtake China after sometime 

With the use of the "on the other hand" shows us that this sentence needs to come later since something else is being compared to India. 

B. But, a direct consequence of these is a situation where China would not have enough young workforce to further develop its economy after a few years.

This sentence is talking about a consequence of a particular something and hence cannot be the starting sentence

C. China’s population is much larger than that of India.

This can be a good starting sentence

D. As a result, China has been able to check its population growth effectively.

We need contextual information to understand the use of this sentence

E. However, in the past two decades, China has enforced strict measures to control its population growth.

Again, we need contextual information to understand this sentence. 

The paragraph starts with C

C is talking about the fact that the population is much larger than that of India. And E is a direct sentence that provides further information and context about the situation. 
D is talking about the direct effect of the actions enforced in setnece E. And sentence B talks about the direct consequence of D. 

Hence, the order of the sentences should be 
CEDBA