Is the sexual drive the strongest drive in a human being? No, of course not.
Before we answer the question, you must understand some things about drives (desires, emotions, etc.). Drives are contextually dependent. What does that mean? A context is the situation in which one finds oneself in the present, including location, whether or not one has eaten, whether or not one has slept, etc., etc. An example of contextual dependence is your possessing a drive to eat because you have not eaten.
Now, drives are also contextually prioritized. This means that a drive can be suppressed by your psyche because of another drive, in a given context (situation). For example, if you have a drive to eat and a drive to sleep at the same time and you haven’t slept for 48 hours, your drive to eat will probably be suppressed and you will go to sleep.
So, what is the most powerful drive in a human being? If you have multiple drives at the same time, the most powerful drive will be the drive that your situation gives power. For example, whenever there are famines and people are starving, the drive for sex will be suppressed and their drive to seek food will be more powerful.
One final note, a human being is not a puppet. Drives do not totally control us. They merely pressure us to go in certain directions. You have free will and, in most situations, you can choose what you will do whether or not it is what your drives want you to do. Note that you should avoid situations that will allow one or more drives to become more powerful than you.