Questions

Ans. C.
The answer is the ‘vilest thing that can be done by a person.' Vile/vilest means extremely unpleasant. Option A: A singular thing is being talked about (indicated by ‘is’) hence, things can’t be used. Option B: ‘is’ indicates singular activity, hence things can’t be used.
Option C: It makes the sentence grammatically and structurally correct.

Auto-immune disease :: Sometimes, due to genetic and other unknown reasons, the body attack self-cells. This results in damage to the body and is called auto-immune disease.

From the options,

-> Rheumatoid arthritis is an autoimmune disorder in which antibodies are produced against the synovial membrane and cartilage.

-> Vitiligo causes white patches on skin also characterised as autoimmune disorder.

-> Psoriasis is a skin disease that causes itchy or sore patches of thick red skin and is also autoimmune.

-> Alzheimer's disease is a chronic neurodegenerative disease. Alzheimer's disease is due to deficiency of neurotransmitter acetylcholine.

Hence, Alzheimer's is not the auto-immune disease.

The    HIV    virus    continuously    invades    and destroys  T-cells  (lymphocytes).  Eventually  the body can't replace the T-cells fast enough, and the  immune  system  deteriorates.  When  the immune  system has deteriorated to the point that it is unable to fight off diseases, a person is diagnosed with AIDS.

The Northwest Ordinance of 1787 was significant because it was the second continental congress that charted a government for territory in Northwest America. It also helped forbid slavery, and made a method of admitting new states near the Union.

World Radio Day is observed on 13th February every year. The Day is organised by UNESCO. This Day is celebrated for 1st time in 2012.

World Radio Day 2019 theme is "Dialogue, Tolerance & Peace".