5
Reading for right to left (backward to normal)
The first 1 is one in base 10 (decimal).
The Zero is null (as in none)
The last (or first reading from left to right) means 4.
4+0+1 = 5
1+0+1 = 5
The triangle indicates that the clock signal is an edge-triggered signal.
The circle indicates that the signal is low-active (ie., inverted).
The 74LS74 has a positive-edge trigger clock (low to high).
The Boolean type is used to represent true or false values
Explanation:
The else statement is usually used when computations are still required when a condition is not met in an if and else-if statement, so the correct option is the fourth one: "to describe what should happen when the condition of an if statement isn't met".
Hope this helps :)