Part A has an error.
The singular verb 'has' should be replaced with its plural verb 'have'. Since the subject 'costs' is a plural noun, we cannot use a singular verb to justify the subject.
Hence, option (d) is the correct answer.
Note:
Subject-Verb Agreement: Matching up singular or plural subjects with singular or plural forms of a verb is part of the process called agreement. This can be understood better by the examples given: - "She likes cooking." [singular subject and verb] -- "They like to cook vegetables." [plural subject and verb]
Study Notes
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