Consider the following plants1.Groundnut2.Horse-gram3.SoybeanHow many of the above belong to the pea family ?

1. A

   Only one

   Only one. All three are legumes.

2. B

   Only two

   Only two. Under-counts.

3. C

   All three

   All three. Groundnut, horse-gram and soybean are Fabaceae.

4. D

   None

   None. All belong to the pea family.

Summary. Official key is (c) all three. Groundnut (Arachis), horse-gram (Macrotyloma) and soybean (Glycine) are legumes — the pea family (Fabaceae).