Which of the following is not true for $Riccia$?

$A$: The gametophytic plant body of bryophytes is a thallus.
$R$: The gametophytic stage of bryophytes is haploid and autotrophic.

In which of the following bryophytes are gemmae found as a means of vegetative reproduction?

Choose the correct statement about liverworts.
$I.$ In liverworts,sexual reproduction occurs by the fusion of antherozoids and egg,which are produced in antheridium and archegonium,respectively.
$II.$ Both male and female sex organs may be present on the same thallus or different thalli.
$III.$ The zygote gives rise to a sporophyte,which is differentiated into foot,seta,and capsule.
$IV.$ Some cells of the capsule undergo meiosis and give rise to haploid spores.

Examine the figure given below and select the correct option identifying all the four parts $(a, b, c$ and $d)$ correctly.

In bryophytes,reproduction occurs through which sex organs?