In mid-summer, a family assembled a patio set for their deck. Most of the assembling was done by placing metal screws into plastic holes. The furniture was stable throughout the summer. However, when the weather turned cold in the late fall, the family noticed that the chairs and table became wobbly. Which statement best explains what happened?

a
Plastic has greater thermal expansion than metal does.
b
Both plastic and metal contract when warm and expand when cold.
c
The metal screws contracted less than the plastic did when they became cold.
d
The metal screws contracted and therefore the table and chairs became wobbly.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

it's c. (to reduce the greenhouse effect/carbon gasses)

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.