D. 1.429 x10^-3
1) A scientific notation is written with a whole number and two decimal places (hundredths) or depending on the number 3 decimal places so examining 0.001429
2) We can rewrite it as 1.429 multiplied by 10 raised to the number of decimal places to the right where 1.4 is located. The exponent is a negative one since
0.001429 is lesser than 1.429.
3) Hence, the answer is :