Replace the underlined noun with the appropriate pronoun.
Jim used a spade to dig the garden. The spade was heavy.
a. it
b. he
c. she
d. who

Hint: Understand the meaning of the given sentence as the context of the sentence will help you to identify the correct and required answer. Try to match the pronoun in the
given sentence to the appropriate one in the given options.

Complete answer:
 Nouns are basically considered naming words. However, one cannot use nouns all the time. So, there are placeholder words that replace nouns, called pronouns. Words like ‘I’, ‘You’, ‘She’, ‘He’,’ They’, and ‘It’ are pronouns.
The noun phrase underlined in the given sentence is ‘the spade’. This means that it is the noun that we need to replace with a pronoun. Let us understand what this word means. The word ‘spade’ refers to ‘. This means that this is an inanimate object, i.e. of neuter gender. So, the pronoun used will be the pronoun used for inanimate objects.

Now, we know what we are looking for. Let’s go through the given options-
a. it - The word ‘it’ is a pronoun that is used to replace inanimate object nouns. This word fits into the given sentence perfectly and can substitute ‘the spade’. This is the required answer. So, this is the correct option.
b. he - The word ‘he’ is a pronoun that is used to replace masculine nouns. This word does not fit into the given sentence perfectly and cannot substitute ‘the spade’. This is not the required answer. So, this is an incorrect option.
c. she - The word ‘she’ is a pronoun that is used to replace feminine nouns. This word does not fit into the given sentence perfectly and cannot substitute ‘the spade’. This is not the required answer. So, this is an incorrect option.
d. who - The word ‘who’ is an interrogative pronoun that is used to demonstrate nouns of any gender. This word does not fit into the given sentence perfectly and cannot substitute ‘the spade’. This is not the required answer. So, this is an incorrect option.

Note:
 Depending on what is underlined and the meaning of the noun, the pronoun to be chosen will change. It is important to realize that the gender of the noun plays a very important role in choosing the correct pronoun.