I would go with C. SDS and warning signs
Explanation:
The given cell reaction is as follows.

Hence, reactions taking place at the cathode and anode are as follows.
At anode ; Oxidation-half reaction :
...... (1)
At cathode; Reduction-half reaction :
....... (2)
Hence, balance the half reactions by multiplying equation (1) by 2 and equation (2) by 3.
Therefore, net cell reaction is as follows.

Net reaction: 
Thus, we can conclude that the overall cell reaction is as follows.

The answer should be (D) Ca, because all others either occur as diatomic or are anions.
The Pascal (symbol: Pa) is the SI derived unit of pressure. It is used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength. It is defined as one Newton per square meter. It is named after the French polymath Blaise Pascal.
The Pascal (Pa) or kilo pascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch.