Step 
<u>find the mass of a single washer</u>
Divide the total mass by the number of washers


Step 
<u>Convert kg to mg</u>
we know that

so

therefore
<u>the answer is</u>

<u>Answer: </u>The correct answer is Option b.
<u>Explanation:</u>
Oxidizing agent is defined as the chemical reagent which helps the other chemical compound to get oxidized and itself gets reduced. The oxidation state for these species gets reduced because they are undergoing reduction reaction.
For the given chemical equation:

Oxidation state of Chromium is getting reduced from +6 to +3 and oxidation state of chlorine getting increased from -1 to 0.
Hence,
acts like and oxidizing agent because it is itself getting reduced to 
Therefore, the correct answer is Option b.
It should be option (A) because conduction is the transfer of heat energy from one place to another by vibrations/motion of the molecules. I hoped I helped.