Questions

'Rare earth'(They are all metals)

A Kitten.

During convection, cool and dense air falls through the warmer and less dense air. The warm air having less mass is being displaced by the cooler which is much heavy. Convection always involves the air rising through the atmosphere.

Answer A is tempting because the problem focuses on changes. However, because we are talking about the elaboration of the product's characteristics, we are talking about scope changes, and therefore Answer B is the best answer. Answer C is also tempting because it is difficult to more forward on a project until the scope is clearly defined (especially in systems development projects), but with products and certain types of web development, scope changes can be frequent, and a formal scope management plan is needed. Answer D is true from a project perspective, but does not addres the scope issues.

Two series alternate here, with every third number following a different pattern.
In the main series, 4 is added to each number to arrive the next.
In alternate series, 5 is subtracted from each number t arrive the next number.
Here in the main series 
3 + 4 = 7
7 + 4 = 11
11 + 4 = 15
15 + 4 = 19

In alternate series 
24 - 5 = 19
19 - 5 = 14...

a -  at the peak of changes in blood pressure indicates the systiolic pressure.