Directions: Identify the letter-number group that completes the analogy. Treat each number as a complete value; do not split it into individual digits.

AB150 : ? :: CD300 : EF320 :: GH500 : IJ520

The correct option is CD170.

To identify the missing letter-number group in the analogy AB150 : ? :: CD300 : EF320 :: GH500 : IJ520, we break down the logic into two separate patterns: the letter pattern and the number pattern.

1. Letter Pattern Analysis:
Let us examine the transition of letters in the given complete pairs:
• Third pair (GH500 : IJ520):
The first letter advances by 2 positions in alphabetical order: G ⇒ I
The second letter advances by 2 positions in alphabetical order: H ⇒ J

• Second pair (CD300 : EF320):
The first letter advances by 2 positions in alphabetical order: C ⇒ E
The second letter advances by 2 positions in alphabetical order: D ⇒ F

Applying this exact +2 alphabetical shift to the first term AB150:
First letter: A + 2 = C
Second letter: B + 2 = D
Thus, the letter group for the missing term is CD.

2. Number Pattern Analysis:
Next, let us look at the numerical values in each pair:

$520-500=20$

$320-300=20$

In each established analogy pair, the second number is formed by adding 20 to the first number. Applying this addition to 150 from AB150:

$150+20=170$

So, the number for the missing term is 170.

Conclusion:
Combining the letter group CD with the numerical value 170 gives CD170.
Hence, the completed analogy is AB150 : CD170 :: CD300 : EF320 :: GH500 : IJ520.