Which one of the following diseases is not the sexually transmitted i…

The correct answer is Option (3) → Thalassemia

Option (1) Chlamydiasis — A sexually transmitted infection. It is caused by a bacterium and passes from person to person through sexual contact. It is completely curable if detected early and treated properly.

Option (2) Trichomoniasis — A sexually transmitted infection. It is caused by a protozoan and spreads through sexual intercourse. It too is curable when treated in time.

Option (3) Thalassemia — Not a sexually transmitted infection. Thalassemia is a Mendelian disorder, an autosome-linked recessive blood disease. A child gets it from both parents who carry the gene. It is caused by a mutation that reduces the synthesis of globin chains of haemoglobin. It is inherited, not caught from anyone, so it is not an infection at all.

Option (4) Gonorrhoea — A sexually transmitted infection. It is a bacterial infection that spreads through sexual contact. It is one of the common STIs and is curable with early treatment.

NCERT Extract:
Sexually Transmitted Infections (STIs) –
Mendelian Disorders – “… Thalassemia : This is also an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous).”