What is frequency vibration?

 Frequency is the rate of vibration and oscillation measured over a specific period of time (usually one second). In layman's terms, it's simply a repeating sequence.

Explanation:

Frequency, which is measured in hertz (Hz) units, is the rate at which vibrations and oscillations occur. Frequencies are used to determine and differentiate vibrational patterns. So, an atom that is vibrating at a faster rate would be considered a higher frequency than one that is vibrating at a much slower rate.

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

your answer is c! hope this : )