(a) To win the war against the bacteria, one must keep the immune system upbeat. (b) People should not spread the droplets in the air by coughing and sneezing openly. (i) Moreover (ii) Additionally (iii) Though

MOREOVER is used to introduce a second clause that builds up on the first, or provides further information – “To win the war against the bacteria, one must keep the immune system upbeat; moreover, people should not spread the droplets in the air by coughing and sneezing openly.” ADDITIONALLY is used to introduce additional or further information – “To win the war against the bacteria, one must keep the immune system upbeat; additionally, people should not spread the droplets in the air by coughing and sneezing openly.” Thus, (b) is the right answer. THOUGH is used to join contradictory clauses or sentences, which is not the case here.