Explanation:

Colour blindness is the inability to see colours in a normal way. Colour-blind individuals often cannot distinguish between certain colours — usually greens and reds, and sometimes blues as well.

• It is also known as colour deficiency.

Anatomy: Two types of cells in the retina detect light:

• Rods: These help in distinguishing between light and dark.
• Cones: These help in detecting colour.

There are three types of cones that see colour — red, green, and blue — and our brains use the information from these cells to perceive colour.

• Colour blindness can be the result of the absence of one or more of these cone cells, or their failure to work properly.

Causes

Congenital Colour Blindness: Most colour blind people are born with the condition (congenital colour blindness). Congenital colour vision deficiencies are usually passed on genetically.

• This type of Colour blindness generally affects both eyes, and the condition remains roughly the same for as long as the individual is alive.

Medical Conditions: A problem with a colour vision that arises later in life could be the result of disease, trauma, or ingested toxins.

• If colour blindness arises out of disease, one eye may be affected differently from the other, and the difficulty could worsen over time.
• Medical conditions that may increase the risk of getting colour blindness include glaucoma, diabetes, Alzheimer’s, Parkinson’s, alcoholism, leukaemia, and sickle-cell anaemia. 

Hence only statement 1st is correct.