Answer:
D, Im not very sure about this but I would say D
Explanation:
I tried
To solve this problem we will apply the concepts related to the Doppler Effect. The Doppler effect is the change in the perceived frequency of any wave movement when the emitter, or focus of waves, and the receiver, or observer, move relative to each other.
Mathematically it can be described as

Where,
v = Speed of sound
f' = Reflected frequency
f = Emitted Frequency
= Speed of the object
Assuming that the speed of the medium is the speed of sound of 343m / s, we will then have that:


The total resistance of an electric circuit with resistors widener series in the sum of the individual resistances:
Each resistor in a series circuit has a same amount of current flowing through it.
Each resistor in a parallel circuit has the same for voltage of the source applied to it.
When was this is are connected in parallel, the supply current is equal to the sum of the current through each resistor. In other words the currents in the branches of a parallel circuit add up to the supply current. When resistors are connected in parallel they have the same potential differences across them.
Answer:
the answer is B
Explanation:
wave x has the highest hertz making it the answer
The answer is Strontium(Sr)