Find the synonym of the underline word.
It is said that brown genes are dominant and blue genes are recessive.
Controlling
a. Docile
b. Dormant
c. Doleful
d. Barren

Hint: Synonyms are a certain set of words that can replace a specific word over and over again. Dominant is a word with a vast number of words to describe it, from controlling, governing, ruling, main, major, that which is above the others, and so on. The antonym of dominant is recessive.

Complete answer:
Now, from the options given above,
Controlling: dominant refers to controlling or governing behavior. Hence, this is the word that gives the same meaning as that of dominant. Eg: Her husband turned out to be so controlling.
Docile: refers to something that can be tamed and controlled. This is the opposite to dominant behavior. Eg: He is a docile kid.
Dormant: refers to a state of inactivity which is not at all in relation to the word given in the question. Eg: Most of the seeds stay dormant during winter.
Doleful: refer to something that is gloomy or in a state of melancholy. Therefore, it is not the answer that we are seeking. Eg: The city seems doleful after the accident.
Barren: refers to dull, something that is not fruitful or fertile. Eg: The land near the mine is barren.

Hence, Option a, is the correct answer to the above question.

Note: Synonyms can take up different forms but their underlying definition stands the same or is similar to the one in hand. All the other words except controlling give off the meaning that is quite opposite to the one in question.