Which answer is true regarding birthday attack on digital signatures? The actual question is:

A sender $S$ sends a message $m$ to receiver $R$, which is digitally
signed by $S$ with its private key. In this scenario, one or more of
the following security violations can take place.
(I) $S$ can launch a birthday attack to replace mm with a fraudulent
message.
(II) A third party attacker can launch a birthday attack to replace
$m$ with a fraudulent message.
(III) $R$ can launch a birthday attack to replace $m$ with a
fraudulent message.
Which of the following are possible security violations?
A. (I) and (II) only
B. (I) only
C. (II) only
D. (II) and (III) only

so if a sender sends a message m to reciever.. I know that an attacker can perform a  birthday attack and send fraudulent message to receiver
But these statements confuse me!

Sender can perform birthday attack and send fraudulent message to Receiver

Receiver can perform birthday attack and create fraudulent message.


I searched upon this but this is too confusing can someone explain? They both seem to be true but the answer i saw states only one is? Can someone explain birthday attack! Thanks
A birthday attacks generates a pair of colliding messages $m, m'$. Because of the way the collision is generated, you can't predict either $m$ or $m'$. If $m$ is fixed, then you need to perform a second-preimage attack instead.

The only person in this scenario who can change $m$ is $S$. $R$ and the third party only receive a fixed message $m$, and have to generate a second preimage $m'$. This is not possible using a birthday attack.

Thus, the correct answer is B. (I) only.