Q.Voltameter measures (A) resistance
(B) potential difference
(C) current
(D) none of these

Electroplating needs a steady one-way current, so DC is used.

Electroplating is based on the chemical (electrolytic) effect of current: the object to be plated is made the cathode, the plating metal the anode, in a solution of the metal's salt. A steady flow of current in one direction makes the positive metal ions move consistently towards the cathode and deposit there.

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A voltameter measures current (the quantity of electricity) through electrolysis — not potential difference.

Do not confuse a voltameter with a voltmeter. A voltmeter measures potential difference, but a voltameter (also called a coulometer) is an electrolytic cell: by Faraday's laws of electrolysis the mass of substance deposited at an electrode is proportional to the quantity of electricity (charge = current × time) passed through it. By measuring the deposited mass one determines the charge, and hence the current. Thus a volta …

Faraday's first law: mass deposited/liberated ∝ charge passed, m = Zq = ZIt.

Faraday's first law of electrolysis states that the mass $m$ of a substance liberated or deposited at an electrode is directly proportional to the quantity of electric charge $q$ (i.e. current $I$ multiplied by time $t$) passed through the electrolytic solution:

$m = Z q = Z I t$ …