Question

what is the meaning of the word in bold?
for three years in a row, swarms of locusts have descended on madagascar, ravaging corn and rice crops in a country where survival depends on subsistence farming. ergo, finding a way to stop the swarms is a top priority.
therefore
nevertheless
arguably
however

Explanation:

"Ergo" is a Latin - derived word. In the context of the sentence, the first part of the sentence presents a situation (locusts ravaging crops in a country dependent on subsistence farming). The second part is a conclusion (finding a way to stop the swarms is a top priority). "Therefore" is a word that is used to introduce a conclusion based on a previous statement or set of statements. "Nevertheless" and "however" are used to show contrast. "Arguably" is used to suggest that something is open to debate. Since the relationship between the two parts of the sentence is one of cause - and - effect (or statement - and - conclusion), "ergo" means "therefore".

Answer:

therefore