To solve the addition problem 229 + 73, we add the corresponding digits in each place value. Starting from the rightmost place value, 9 + 3 equals 12. We write down the 2 and carry over the 1 to the next place value. Moving to the next place value, 2 + 7 + 1 equals 10. We write down the 0 and carry over the 1 to the next place value. Finally, in the leftmost place value, we add the carried over 1 to 2, resulting in 3. Therefore, the correct answer is 302.