The sentence that presents the correct subject-verb agreement is the first one since in it we are talking about "heavy rains" OR "fast-melting snow". In other words, the subject is coordinated by the conjunction "OR" which makes the subject singular. The verb "causes" is conjugated in the third person singular.
A). Heavy rains or fast-melting snow causes floods in many parts of the world.
Explanation:
Subject-verb agreement is demonstrated as the grammatical rule which implies the agreement of subject and verb in terms of number. It implies that a singular noun must correspond to a singular verb while a plural must correspond to a plural verb.
As per the question, option A implies a correct subject-verb agreement as it includes the subjects 'Heavy rains' and 'fast-melting snow' are linked by coordinating conjunction 'or' that turns it singular and therefore, the verb must also be 'singular'(causes). Thus, <u>option A</u> is the correct answer as in option B the subject and verb do not agree in number.
