on the receipt of will replace of the receipt of.
Look at the examples given below :
The department is authorized, on receipt of such report, to direct an inquiry.
Come as soon as you can on receipt of this.
Hence, on the receipt of this letter is the right usage.

Correct Option: C

on the receipt of will replace of the receipt of.
Look at the examples given below :
The department is authorized, on receipt of such report, to direct an inquiry.
Come as soon as you can on receipt of this.
Hence, on the receipt of this letter is the right usage.

know will replace am knowing because –
know is not used in Progressive/Continuous Tense.
Look at the example given below :
I am knowing that this is true. (×)
I know that this is true. ( )
Hence, know (Simple Present) is used here.

Correct Option: B

know will replace am knowing because –
know is not used in Progressive/Continuous Tense.
Look at the example given below :
I am knowing that this is true. (×)
I know that this is true. ( )
Hence, know (Simple Present) is used here.

you and me will replace you and I because between is a Prep.
A Prep. must be followed by an Indirect object Pronoun.
Me is an Indirect Object Pronoun (Objective Case) while I is a Subject Pronoun. (Subjective or Nominative Case) Therefore, between has to be followed by you and me.
Look at the examples given below :
She went with I. (×)
She went with me. ( )
This is between Tom and I. (×)
This is between Tom and me. ( )

Correct Option: C

you and me will replace you and I because between is a Prep.
A Prep. must be followed by an Indirect object Pronoun.
Me is an Indirect Object Pronoun (Objective Case) while I is a Subject Pronoun. (Subjective or Nominative Case) Therefore, between has to be followed by you and me.
Look at the examples given below :
She went with I. (×)
She went with me. ( )
This is between Tom and I. (×)
This is between Tom and me. ( )

doesn’t it will replace isn’t it because –
Positive statement (without Aux.) takes Negative Tag (with Aux.)
Look at the examples below :

Correct Option: C

doesn’t it will replace isn’t it because –
Positive statement (without Aux.) takes Negative Tag (with Aux.)
Look at the examples below :

many will replace much because –
Stars are Countable Nouns and many is used with Countable Nouns whereas much is used with Uncountable Nouns.
Look at the examples given below :
There was too much traffic on the road.
Many people feel that the law should be changed.
Hence, how many are is the right usage

Correct Option: B

many will replace much because –
Stars are Countable Nouns and many is used with Countable Nouns whereas much is used with Uncountable Nouns.
Look at the examples given below :
There was too much traffic on the road.
Many people feel that the law should be changed.
Hence, how many are is the right usage