The organisms “Cicada, Froghopper and Pond skater” are:

The correct option is Insects.

To understand why this is the correct classification, we can examine the biological characteristics of each of the three organisms:
1. Cicadas: These are winged insects known for their distinct, loud mating calls produced by males using specialized organs called tymbals. They belong to the order Hemiptera (true bugs).
2. Froghoppers: These are small, jumping insects also belonging to the order Hemiptera. Their nymphs are famously known for producing a protective frothy secretion that resembles spit, commonly referred to as "spittle."
3. Pond skaters: Often called water striders, these are semi-aquatic insects belonging to the family Gerridae. They are known for their ability to walk on the surface of water, utilizing surface tension and the hydrophobic (water-repelling) hairs on their long legs.

Why they belong to the class Insects (Insecta):
All three of these organisms share the defining anatomical features of the class Insecta:
- They have a chitinous exoskeleton.
- Their bodies are divided into three distinct regions: a head, a thorax, and an abdomen.
- They possess three pairs of jointed legs (total of six legs) attached to the thorax, and typically have antennae.

Why other options are incorrect:
- Birds are warm-blooded vertebrates characterized by feathers, toothless beaked jaws, and laying hard-shelled eggs.
- Fish are gill-bearing aquatic craniate animals that lack limbs with digits.
- Reptiles are cold-blooded vertebrates covered in scales or bony plates, such as lizards, snakes, and turtles.