Answer: The correct spelling is a. scissors.
Explanation: The word 'scissors' is a noun and it makes reference to a tool used mainly for cutting paper. Moreover, 'scissors' is one of the few nouns that only has a plural form, that is to say 'scissors' does not have a singular form (it is incorrect saying 'scissor'). In that way, as it is a plural noun, it must be followed by a plural verb, such as "are". Therefore, the correct spelling among the options is A.
