The correct answer is option (A):
robust … leverage
The correct answer is "robust … leverage". Let's break down why and why the others are less suitable.
The sentence describes a strategic situation for India. The goal is to strengthen India's position concerning its relationships with the US, China, and Russia.
* "Robust" means strong and healthy. A strong relationship with Moscow (Russia) would provide India with considerable influence, or "leverage", in its dealings with other major powers like Washington (the US) and Beijing (China).
* "Leverage" in this context implies using one relationship to improve or strengthen others.
Now let's look at the other options:
* "Healthy … enhance": While a healthy relationship is a good thing, "enhance" is less impactful than "leverage." "Enhance" means to improve something, but "leverage" implies a more active, strategic benefit.
* "Mutual … lose": "Mutual" means shared or reciprocal, which could apply, but "lose" is the opposite of the desired effect, which is to strengthen ties.
* "Perfect … ally": While India and Russia have historically been allies, "perfect" is too strong of a word. Also, the second blank needs a verb that reflects a strategic benefit, not just becoming an ally.
* "Vigorous … cement": "Vigorous" means energetic, similar to robust. While "cement" means to strengthen or make something firm, "leverage" is still the better word choice to show how the relationship with Russia can be used to influence relationships with other countries.