Which term from among the given options can replace the question mark (?) in the following series to make it logically complete?
WG 12, UE 15, ?, QA 21, OY 24

Correct option is C

Given series: WG 12, UE 15, ?, QA 21, OY 24

First Letter Logic:

W → U (W - 2 = U)

U → S (U - 2 = S) ← First letter of the missing term.

Q → O (Q - 2 = O)

Second Letter Logic:

Now let's look at the second letter in the series:

G → E: The second letter G decreases by 2 alphabet positions to become E.

E → C: The second letter E decreases by 2 alphabet positions to become C (This will be the second letter for the missing term).

A → Y: The second letter A decreases by 2 alphabet positions to become Y.

Number Logic:

12 → 15 (+3)

15 → 18 (+3) ← The number for the missing term.

21 → 24 (+3)

Putting it all together:

First letter: S (U - 2 = S)

Second letter: C (E - 2 = C)

Number: 18 (15 + 3 = 18)

So, the missing term is SC 18.

Thus, the correct answer is (c) SC 18.

Alternate Method: