Explanation:

Let’s break it down step by step:

- Let's look at the differences between the numbers:

20 - 14 = 6

34 - 20 = 14

70 - 34 = 36

134 - 70 = 64

234 - 134 = 100

378 - 234 = 144

- Notice these differences: 6, 14, 36, 64, 100, 144

- These numbers don’t follow a clear, simple pattern like squares or even any easy increments.

- But if we check the expected pattern, maybe the intention was for the differences to be perfect squares:

- 2² = 4

- 3² = 9

- 4² = 16

- 5² = 25

- 6² = 36

- 7² = 49

- 8² = 64

- 9² = 81

- 10² = 100

- 12² = 144

- If we change 70 to 68 (checking for other possible errors):

68 - 34 = 34 (not perfect square)

- But if we change 134 to 170:

170 - 70 = 100 (correct)

234 - 170 = 64 (should be 64, but it’s 64)

But again, that doesn't restore the sequence to a known pattern.

- Let's try changing 20 to something else:

If the first number is 14, let's see what happens if we have second number = 18 (difference of 4):

34 - 18 = 16, which is 4².

And so on—but this doesn't fit the rest either.

- Actually, looking at 70:

34 + 36 = 70 (difference is 36, which is 6²)

So, maybe the difference sequence was supposed to be: 6 (ignored), 14, 36, 64, 100, 144 — but 14 is not a perfect square.

- If 34 was wrong, then 20 + 16 = 36 (difference 16, which is 4²), but then following numbers are off.

- Let's consider the sequence is intended as:

14, then add 6 (20), then add 16 (36), then 36 (72), then 64 (136), then 100 (236), then 144 (380)

But 20 is not fitting as per any logical square or addition sequence.

Hence, the odd one out is:

- 20

Option 3: 20

In summary:

- The sequence doesn’t follow the pattern of differences (squares or otherwise) if 20 is present, making it the wrong number.

- Other options (70, 134, 234, 14) have their differences fitting better with the squared numbers pattern or, at least, do not disrupt it as much as 20 does.

- So, the correct answer is Option 3: 20.