Find the missing number from the given alternatives.

6	10	14
9	15	21
12	20	?

Looking at the table:

6	10	14
9	15	21
12	20	?

Examining the rows, each row forms an arithmetic sequence:

Row 1: $6, 10, 14$ with common difference $4$

Row 2: $9, 15, 21$ with common difference $6$

Row 3: $12, 20, ?$ with common difference $8$

Following this pattern: $? = 20 + 8 = 28$

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Examining the columns to verify:

Column 1: $6, 9, 12$ with common difference $3$

Column 2: $10, 15, 20$ with common difference $5$

Column 3: $14, 21, ?$ with common difference $7$

Following this pattern: $? = 21 + 7 = 28$

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Alternatively, observing the structure as products:

Column 1: $6 = 2 \times 3$, $9 = 3 \times 3$, $12 = 4 \times 3$

Column 2: $10 = 2 \times 5$, $15 = 3 \times 5$, $20 = 4 \times 5$

Column 3: $14 = 2 \times 7$, $21 = 3 \times 7$, $? = 4 \times 7 = 28$

Each column multiplies consecutive odd numbers $(3, 5, 7)$ by the row position $(2, 3, 4)$.

Therefore, the missing number is $28$.