SELF DOUBT

Question

PLEASE ANYONE REFER ANY VIDEO OF DATA HAZARDS OR SOME NOTES SOME LINK……………...NOT  GETTING ENOUGH EXPLANATION OF DATA HAZARD HERE .

IF SOMEONE KNOWS THE CONCEPT THEN

Consider the following Instruction sequence  
I1: ADD R1,R2,R1
I2: LW R2,0(R1)
I3: LW R1,4(R1)
I4: OR R3,R1,R2
And assume following five stage pipeline with following stages:  
IF,ID,EXE,MEM,WB  
The no of RAW hazards in the above Instruction sequence is?  
(A) 3  
(B) 2  
(C) 4  
(D) 1

then plss explain this question solution step by step otherwise give the link ? and cases like with pipelining without pipelining

Comments

i have said in the context of dependency.

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@Gupta731 @Shaik Masthan

How you people are getting option B.

In instructions (1,2) , (1,3) and (1,4) for $R_1$ and (2,4) for $R_2$

So there are 4 RAW hazards

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The answer should be (c) 4.
RAW:

I1-I2(R1)

I1-I3(R1)

I2-I4(R2)

I3-I4(R1)
It is an exercise question of  Hennessy and Patterson's book.