Assertion: The sporogonium of Riccia is the simplest among the liverworts.
Reason: Sporophyte consists of capsules only.
A. If both assertions and the reason are true and the reason is a correct explanation of assertion.
B. If both assertion and reason are true but the reason is not the correct explanation for the assertion.
C. If the assertion is true but the reason is false.
D. If both the assertion and reason are false.

Hint: Riccia belongs to class liverwort. Riccia has the simplest and primitive type of sporogonium that is only differentiated in a capsule. Liverworts are included in Bryophytes.

Complete answer: The sporophyte of a moss or liverwort containing typically of a stalk bearing a capsule in which spores are produced, developing from a fertilized egg in the center of the archegonium, and remaining permanently attached to the gametophyte by the base of the stalk which acts as an absorbing organ.
Bryophytes’ dominant stage is gametophyte.
It is haploid and free living.
The sporophyte stage is diploid, short-living, and dependent on the gametophyte.
The sporophyte plant body is differentiated in foot, seta, and capsule.
But in Riccia, unlike others, the sporophyte plant body is differentiated in capsule only. No foot, seta, capsules are found. The sporophyte is found embedded in the gametophyte.

So, the correct answer is “Option A”.

Note: Capsule of sporophyte is also called spore sac. In capsule diploid spores are found.
The sporophyte stage of bryophytes is also called sporogonium that is differentiated in the foot, seta, and capsule. As a primitive member of bryophytes in Riccia, the sporophyte stage is only differentiated in the capsule so this is called as simplest.