Antonym of the given word

abet 

Here the given words Careful and Cautious are related in such a way that they are Synonyms of each other.

Therefore, Similarly Boastful is synonym to the word Arrogant.

Happily and Humble are Antonyms of Boastful and Surprisingly is the word not related to Boastful in any way.

So, Careful is to Cautious as Boastful is to Arrogant.

Here Lizard is a type of Reptiles whereas Orchid is a type of flowers. Other than Orchids all are parts of Plants.

Hence, Reptile is to Lizard as Flower is to Orchids.

Yard is to Inch as Quart is to Ounce.

Because Yard and Inch are units of measurement Where Yard is larger than Inch i.e, 1 Yard = 36 Inches.

So, here Quart and Ounce are also units of measurement where Quart is larger than Ounce i.e, 1 Quart = 32 Ounces.

Gallon is not correct because Gallon is larger than Quart and Milk and Liquid are not units of measurement.

So, Ounce is correct.

Cup : Coffee :: Bowl : Soup

Because Coffee goes into a Cup and Soup goes into a Bowl where Food is a general thing and Mug is an other utensil. 

So, Cup is to Coffee as Bowl is to Soup.

Fence protects the Yard & Membrane protects the Cell.

Fence surrounds the Yard and allows the certain objects in & out of it whereas a Membrane surrounds the Cell & only allows specific nutrients inside of it.

Hence, Yard is to Fence as Cell is to Membrane.

A biped is an animal that uses two legs for walking and the quadrupeds are animals that use four legs for walking.

From the Given options, Cat only have 4 legs.

So Biped : Quadruped :: Ostrich : Cat.

Detailed description of a man's life is Biography.

Similarly, detailed description of a Nations is called History.

7 C in a R represents 7 Colours in a Rainbow.