Answer:
Option D - 
Step-by-step explanation:
Given : The mass of a dust particle is 0.000000000735 kilograms.
To find : What is the mass written in scientific notation?
Solution :
Scientific notation is writing a number into smaller or larger number.
Mostly scientific number is in a number before decimal and then the multiple of 10 to the powers.
So, 

The mass in scientific notation is
kg.
Therefore, Option D is correct.