When the transactions happens inside the platform, the platform is responsible for the following

$($i$)$ Reliability of the transaction

$($ii$)$ Quality of the transaction

$($iii$)$ Intermediating the risk and efficiency of completing the contract

a$.$

$($i$)$ and $($ii$)$

b$.$

$($ii$)$ and $($iii$)$

c$.$

$($i$),($ii$)$ and $($iii$)$

d$.$

$($i$)$ and $($iii$)$