Well,
For the first one, the answer would be C, because all organisms in Kingdom Animalia must eat in order to survive.
For the second one, all of the options are in Kingdom Animalia, but worms (A) and clams (C) are invertebrates. So that leaves options B and D.
They both are mechanical waves.
Explanation:
Echolocation and ultrasounds are both mechanical waves that require a medium to trace through. They both process and transfer information through waves; the difference is that we humans cannot hear ultrasound waves.
Answer:

Explanation:
Given that,
The instantaneous current in the circuit is giveen by :

We need to find the rms value of the current.
The general equation of current is given by :

It means, 
We know that,

So, the rms value of current is 2.12 A.
Respiratory system.
Oversimplified Explanation: they enter the lungs, which is part of the respiratory system.