In the question below, two sentences are given and each

Solution

I - We need a noun in 1 to be modified by the adjective POOR. In 2, we need an adjective to modify the noun COUNTRIES. The sentence says that it is a well-known fact that low standards of cleanliness and hygiene are a major cause of diseases in underdeveloped countries. Although EFFICACY (efficiency) and REGULATORY (governing) fit structurally, they are contextually inappropriate for 1 and 2, respectively. EFFICACY should be replaced with SANITATION (cleanliness) and REGULATORY should be replaced with DEVELOPING (not yet developed). II - The sentence says that once a vaccine candidate is proven safe and effective, it is submitted to authorised agencies for full approval. Although SANITATION fits structurally, it is not an attribute of a vaccine. It should be replaced with EFFICACY. Similarly, DEVELOPING, which fits structurally, is not an appropriate adjective for agencies that monitor the creation of vaccines. It should be replaced with REGULATORY.