Convection is the transfer of heat from
a. warmer objects to cooler objects in liquids and gases.
b. cooler objects to warmer objects in liquids and gases.
c. cooler objects to warmer objects by direct contact.

warmer objects to cooler objects in liquids and gases

The natural convection is a process, in which the fluid movement occurs from heat transfer. When a fluid is warmed or chilled, its density changes and the buoyancy effect create a natural flow in the affected region, which makes itself the rise of hotter fluid and the fall of cooler fluid: hence, energy transfer from hotter area to colder area and such process is repeated as long as the temperature variation in fluid exist.

meiosis is required for sexual reproduction

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."