Your teammate is spinning a tennis ball on a string in a perfect circle. If the radius of the circle is 45 cm and the ball travels half the circumference of the circle in 15 seconds, what is the velocity of the ball rounded to the nearest whole number?
A
3 m/s
B)
30 cm/s
94 cm/s
D)
212 cm/s

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.

they are known as evergreens