Replace the underlined noun with the appropriate pronoun.
Jim used a spade to dig the garden. The spade was heavy.
A pronoun takes the place of a noun in a sentence. A personal pronoun is a pronoun that is associated with a particular person, like ‘he’, ‘she’ and ‘they’. While an impersonal pronoun is commonly used to speak about inanimate objects/things. ‘It’ is an impersonal pronoun that is used for this purpose. In the given sentence the noun is a ‘spade’ therefore ‘it’ would be the apt answer. Thus option D is correct. On the other hand, ‘he’ and ‘she’ cannot be used since ‘spade’ is not a person. Thus options A and B are incorrect. ‘Who’ is an interrogative pronoun that is used to for asking questions. Since the sentence doesn’t pose a question, option C is incorrect.