C.

In oomycetes female gamete is smaller and motile, while male gamete is larger and non-motile

Oomycetes (egg fungus) include water moulds, white rusts and downy mildews. In these, white rusts and downy mildews. In these, female gamete is smaller and motile, whereas male gamete is larger and non-motile. 
Isogametes are found in algae like Ulothrix, Chlamydomonas, Spirogyra etc., which are similar in structure, function and behaviour. 
Anisogametes are found in Chlamydomonas in which one gamete is larger and non-motile and the other one is motile and smaller.
Oogamy is the fusion of non-motile egg with motile sperm. The gametes differ both morphologically as well as physiologically. It occurs in Chlamydomonas, Fucus Chara, Volvox, etc

C.

A museum has collection of photographs of plants and animals

Museums have a collection of preserved plants and animal specimens for study and reference specimens are preserved in the containers in preservative solutions.
Herbarium is a store house at collected plant specimens that are dried, pressed and preserved on sheets.
Botanical gardens have a collection of living plants for reference.
The key is a taxonomic aid for identification of plants and animals based on the similarities and dissimilarities.

B.

Spirogyra

Isogamy is found in Spirogyra in which both gametes are non-motile.In Chlamydomonas, all three conditions, isogamy anisogamy and oogamy are found.Both motile and non-motile gametes are found. In volvox and Fucus, oogamy is present, where non-motile egg fuses with motile sperm.

B.

Cycas

Cyanobacteria within the coralloid roots of Cycas are chemoheterotrophic and specifically adapted to life in symbiosis. Only a few species of cyanobacteria form associations with Cycas. Pinus is gymnosperm.Equisetum belongs to vascular plants and to horse tail family.Psilotum belongs to division -Pteridophyta and is a fern like a plant.

C.

Fifteen

Pulm, rose are perigynous and guava, cucumber are epigynous. So, total remaining plants are hypogynous.